Skip to content

M
MariaDB
Commit 357788e8 authored by unknown's avatar unknown
Browse files
Options

NuSphere editor's changes to pages 151-200 of manual.texi. 


Docs/manual.texi:
  NuSphere editor's changes to pages 151-200.
parent f40b8ab3
Hide whitespace changes
Inline Side-by-side
Showing with 275 additions and 275 deletions
Docs/manual.texi
View file @ 357788e8
......@@ -11557,7 +11557,7 @@ have the necessary privileges to perform the request, but the server cannot
tell that from either table by itself; the privileges granted by the entries
in both tables must be combined.
The @code{host} table can be used to maintain a list of ``secure'' servers.
The @code{host} table can be used to maintain a list of secure servers.
At TcX, the @code{host} table contains a list of all machines on the local
network. These are granted all privileges.
......@@ -11577,12 +11577,12 @@ like this:
+--------------------+----+-
@end example
Naturally, you should always test your entries in the grant tables (e.g.,
using @code{mysqlaccess}) to make sure your access privileges are actually
set up the way you think they are.
Naturally, you should always test your entries in the grant tables (for
example, using @code{mysqlaccess}) to make sure your access privileges are
actually set up the way you think they are.
@node Privilege changes, Default privileges, Request access, Privilege system
@section When privilege changes take effect
@section When Privilege Changes Take Effect
When @code{mysqld} starts, all grant table contents are read into memory and
become effective at that point.
......@@ -11615,7 +11615,7 @@ Global privilege changes and password changes take effect the next time the
client connects.
@node Default privileges, Adding users, Privilege changes, Privilege system
@section Setting up the initial MySQL privileges
@section Setting Up the Initial MySQL Privileges
After installing @strong{MySQL}, you set up the initial access privileges by
running @code{scripts/mysql_install_db}.
......@@ -11629,7 +11629,7 @@ of privileges:
The @strong{MySQL} @code{root} user is created as a superuser who can do
anything. Connections must be made from the local host.
@strong{Note:}
@strong{NOTE:}
The initial @code{root} password is empty, so anyone can connect as @code{root}
@emph{without a password} and be granted all privileges.
......@@ -11660,7 +11660,8 @@ mysql> UPDATE user SET Password=PASSWORD('new_password')
mysql> FLUSH PRIVILEGES;
@end example
You can in @strong{MySQL} 3.22 and above use the @code{SET PASSWORD} statement:
You can, in @strong{MySQL} Version 3.22 and above, use the @code{SET PASSWORD}
statement:
@example
shell> mysql -u root mysql
......@@ -11673,13 +11674,13 @@ Another way to set the password is by using the @code{mysqladmin} command:
shell> mysqladmin -u root password new_password
@end example
Only user with write/update access to the mysql database can change the
password for others user. All normal users (not anonymous ones) can only
change his own password with either of the above commands or with
@code{SET PASSWORD=PASSWORD('new password')}
Only users with write/update access to the mysql database can change the
password for others users. All normal users (not anonymous ones) can only
change their own password with either of the above commands or with
@code{SET PASSWORD=PASSWORD('new password')}.
Note that if you update the password in the @code{user} table directly using
the first method, you must tell the server to reread the grant tables (with
the first method, you must tell the server to re-read the grant tables (with
@code{FLUSH PRIVILEGES}), because the change will go unnoticed otherwise.
Once the @code{root} password has been set, thereafter you must supply that
......@@ -11696,20 +11697,20 @@ add other users.
If you want the initial privileges to be different than those just described
above, you can modify @code{mysql_install_db} before you run it.
To recreate the grant tables completely, remove all the @file{*.frm},
@file{*.MYI} and @file{*.MYD} files in the directory containing the
To re-create the grant tables completely, remove all the @file{.frm},
@file{.MYI}, and @file{.MYD} files in the directory containing the
@code{mysql} database. (This is the directory named @file{mysql} under
the database directory, which is listed when you run @code{mysqld
--help}.) Then run the @code{mysql_install_db} script, possibly after
editing it first to have the privileges you want.
@strong{NOTE:} For @strong{MySQL} versions older than 3.22.10, you should NOT
delete the @file{*.frm} files. If you accidentally do this, you should
copy them back from your @strong{MySQL} distribution before running
@code{mysql_install_db}.
@strong{NOTE:} For @strong{MySQL} versions older than Version 3.22.10,
you should NOT delete the @file{.frm} files. If you accidentally do this,
you should copy them back from your @strong{MySQL} distribution before
running @code{mysql_install_db}.
@node Adding users, Passwords, Default privileges, Privilege system
@section Adding new user privileges to MySQL
@section Adding New User Privileges to MySQL
You can add users two different ways: by using @code{GRANT} statements
or by manipulating the @strong{MySQL} grant tables directly. The
......@@ -11748,14 +11749,14 @@ use a password @code{'some_pass'} to do so. Note that we must issue
@code{monty@@"%"}. If we don't add the entry with @code{localhost}, the
anonymous user entry for @code{localhost} that is created by
@code{mysql_install_db} will take precedence when we connect from the local
host, because it has a more specific @code{Host} field value and thuse comes
host, because it has a more specific @code{Host} field value and thus comes
earlier in the @code{user} table sort order.
@item admin
A user who can connect from @code{localhost} without a password and who is
granted the @strong{reload} and @strong{process} administrative privileges.
This allows the user to execute the @code{mysqladmin reload},
@code{mysqladmin refresh} and @code{mysqladmin flush-*} commands, as well as
@code{mysqladmin refresh}, and @code{mysqladmin flush-*} commands, as well as
@code{mysqladmin processlist} . No database-related privileges are granted.
(They can be granted later by issuing additional @code{GRANT} statements.)
......@@ -11784,9 +11785,9 @@ mysql> FLUSH PRIVILEGES;
@end example
Depending on your @strong{MySQL} version, you may have to use a different
number of @code{'Y'} values above (versions prior to 3.22.11 had fewer
number of @code{'Y'} values above (versions prior to Version 3.22.11 had fewer
privilege columns). For the @code{admin} user, the more readable extended
@code{INSERT} syntax that is available starting with 3.22.11 is used.
@code{INSERT} syntax that is available starting with Version 3.22.11 is used.
Note that to set up a superuser, you need only create a @code{user} table
entry with the privilege fields set to @code{'Y'}. No @code{db} or
......@@ -11798,9 +11799,9 @@ are assigned the default value of @code{'N'}. This is the same thing that
@code{GRANT USAGE} does.
The following example adds a user @code{custom} who can connect from hosts
@code{localhost}, @code{server.domain} and @code{whitehouse.gov}. He wants
@code{localhost}, @code{server.domain}, and @code{whitehouse.gov}. He wants
to access the @code{bankaccount} database only from @code{localhost},
the @code{expenses} database only from @code{whitehouse.gov} and
the @code{expenses} database only from @code{whitehouse.gov}, and
the @code{customer} database from all three hosts. He wants
to use the password @code{stupid} from all three hosts.
......@@ -11856,7 +11857,7 @@ allow user @code{custom} to connect from the various hosts with the given
password, but grant no permissions to him (all privileges are set to the
default value of @code{'N'}). The next three @code{INSERT} statements add
@code{db} table entries that grant privileges to @code{custom} for the
@code{bankaccount}, @code{expenses} and @code{customer} databases, but only
@code{bankaccount}, @code{expenses}, and @code{customer} databases, but only
when accessed from the proper hosts. As usual, when the grant tables are
modified directly, the server must be told to reload them (with
@code{FLUSH PRIVILEGES}) so that the privilege changes take effect.
......@@ -11879,14 +11880,14 @@ mysql> INSERT INTO user VALUES ('%.mydomainname.com', 'myusername',
mysql> FLUSH PRIVILEGES;
@end example
You can also use @code{xmysqladmin}, @code{mysql_webadmin} and even
You can also use @code{xmysqladmin}, @code{mysql_webadmin}, and even
@code{xmysql} to insert, change and update values in the grant tables.
You can find these utilities in the
@uref{http://www.mysql.com/Downloads/Contrib/,Contrib directory of the @strong{MySQL}
Website}.
@node Passwords, Access denied, Adding users, Privilege system
@section How to set up passwords
@section How to Set Up Passwords
@cindex Passwords, setting
@findex PASSWORD()
......@@ -11953,14 +11954,13 @@ shell> mysqladmin -u jeffrey password biscuit
@end example
@strong{NOTE:} @code{PASSWORD()} does not perform password encryption in the
same way that Unix passwords are encrypted. You should not assume that if
your Unix password and your @strong{MySQL} password are the same, that
same way that UNIX passwords are encrypted. You should not assume that if
your UNIX password and your @strong{MySQL} password are the same, that
@code{PASSWORD()} will result in the same encrypted value as is stored in the
Unix password file.
@xref{User names}.
UNIX password file. @xref{User names}.
@node Access denied, , Passwords, Privilege system
@section Causes of @code{Access denied} errors
@section Causes of @code{Access denied} Errors
If you encounter @code{Access denied} errors when you try to connect to the
@strong{MySQL} server, the list below indicates some courses of
......@@ -12010,11 +12010,11 @@ host.
@item
@cindex @code{mysql_fix_privilege_tables}
If you updated an existing @strong{MySQL} installation from a pre-3.22.11
version to 3.22.11 or later, did you run the
If you updated an existing @strong{MySQL} installation from a version earlier
than Version 3.22.11 to Version 3.22.11 or later, did you run the
@code{mysql_fix_privilege_tables} script? If not, do so. The structure of
the grant tables changed with @strong{MySQL} 3.22.11 when the @code{GRANT}
statement became functional.
the grant tables changed with @strong{MySQL} Version 3.22.11 when the
@code{GRANT} statement became functional.
@item
If your privileges seem to have changed in the middle of a session, it may be
......@@ -12025,7 +12025,7 @@ client connections, but it also affects existing connections as indicated in
@item
If you can't get your password to work, remember that you must use
the @code{PASSWORD()} function if you set the password with the
@code{INSERT}, @code{UPDATE} or @code{SET PASSWORD} statements. The
@code{INSERT}, @code{UPDATE}, or @code{SET PASSWORD} statements. The
@code{PASSWORD()} function is unnecessary if you specify the password using
the @code{GRANT ... INDENTIFIED BY} statement or the @code{mysqladmin
password} command.
......@@ -12036,7 +12036,7 @@ password} command.
default host to which clients try to connect if you specify no host
explicitly. However, connections to @code{localhost} do not work if you are
running on a system that uses MIT-pthreads (@code{localhost} connections are
made using Unix sockets, which are not supported by MIT-pthreads). To avoid
made using UNIX sockets, which are not supported by MIT-pthreads). To avoid
this problem on such systems, you should use the @code{--host} option to name
the server host explicitly. This will make a TCP/IP connection to the
@code{mysqld} server. In this case, you must have your real hostname in
......@@ -12074,11 +12074,11 @@ row in the @code{user} table that matches that host:
Host ... is not allowed to connect to this MySQL server
@end example
You can fix this by using the command line tool @code{mysql} (on the
server host!) to add a row to the @code{user}, @code{db} or @code{host}
You can fix this by using the command-line tool @code{mysql} (on the
server host!) to add a row to the @code{user}, @code{db}, or @code{host}
table for the user/hostname combination from which you are trying to
connect and then execute @code{mysqladmin flush-privileges}. If you are
not running @strong{MySQL} 3.22 and you don't know the IP number or
not running @strong{MySQL} Version 3.22 and you don't know the IP number or
hostname of the machine from which you are connecting, you should put an
entry with @code{'%'} as the @code{Host} column value in the @code{user}
table and restart @code{mysqld} with the @code{--log} option on the
......@@ -12109,7 +12109,7 @@ IP to a hostname. In this case you can execute @code{mysqladmin
flush-hosts} to reset the internal DNS cache. Some permanent solutions
are:
@itemize @bullet
@itemize @minus
@item
Try to find out what is wrong with your DNS server and fix this.
@item
......@@ -12130,13 +12130,13 @@ If @code{mysql -u root test} works but @code{mysql -h your_hostname -u root
test} results in @code{Access denied}, then you may not have the correct name
for your host in the @code{user} table. A common problem here is that the
@code{Host} value in the user table entry specifies an unqualified hostname,
but your system's name resolution routines return a fully-qualified domain
but your system's name resolution routines return a fully qualified domain
name (or vice-versa). For example, if you have an entry with host
@code{'tcx'} in the @code{user} table, but your DNS tells @strong{MySQL} that
your hostname is @code{'tcx.subnet.se'}, the entry will not work. Try adding
an entry to the @code{user} table that contains the IP number of your host as
the @code{Host} column value. (Alternatively, you could add an entry to the
@code{user} table with a @code{Host} value that contains a wildcard---for
@code{user} table with a @code{Host} value that contains a wild card---for
example, @code{'tcx.%'}. However, use of hostnames ending with @samp{%} is
@emph{insecure} and is @emph{not} recommended!)
......@@ -12154,7 +12154,7 @@ in the @code{user} table or the @code{db} table.
@item
If you can't figure out why you get @code{Access denied}, remove from the
@code{user} table all entries that have @code{Host} values containing
wildcards (entries that contain @samp{%} or @samp{_}). A very common error
wild cards (entries that contain @samp{%} or @samp{_}). A very common error
is to insert a new entry with @code{Host}=@code{'%'} and
@code{User}=@code{'some user'}, thinking that this will allow you to specify
@code{localhost} to connect from the same machine. The reason that this
......@@ -12201,7 +12201,7 @@ sure you haven't specified an old password in any of your option files!
@xref{Option files}.
@item
If you make changes to the grant tables directly (using @code{INSERT} or
If you make changes to the grant tables directly (using an @code{INSERT} or
@code{UPDATE} statement) and your changes seem to be ignored, remember
that you must issue a @code{FLUSH PRIVILEGES} statement or execute a
@code{mysqladmin flush-privileges} command to cause the server to re-read
......@@ -12212,7 +12212,7 @@ specify it until after you flush the privileges, because the server
won't know you've changed the password yet!
@item
If you have access problems with a Perl, PHP, Python or ODBC program, try to
If you have access problems with a Perl, PHP, Python, or ODBC program, try to
connect to the server with @code{mysql -u user_name db_name} or @code{mysql
-u user_name -pyour_pass db_name}. If you are able to connect using the
@code{mysql} client, there is a problem with your program and not with the
......@@ -12244,12 +12244,12 @@ feel you must post the problem to the mailing list, always provide a
dump of the @strong{MySQL} grant tables. You can dump the tables with
the @code{mysqldump mysql} command. As always, post your problem using
the @code{mysqlbug} script. @xref{Bug reports}. In some cases you may need
to restart @code{mysqld} with @code{--skip-grant-tables} to be able to run
to restart @code{mysqld} with @code{--skip-grant-tables} to run
@code{mysqldump}.
@end itemize
@node Reference, Table types, Privilege system, Top
@chapter MySQL language reference
@chapter MySQL Language Reference
@menu
* Literals:: Literals: how to write strings and numbers
......@@ -12296,7 +12296,7 @@ to restart @code{mysqld} with @code{--skip-grant-tables} to be able to run
@cindex Strings
@cindex Strings, escaping characters
@node Literals, Variables, Reference, Reference
@section Literals: how to write strings and numbers
@section Literals: How to Write Strings and Numbers
@menu
* String syntax:: Strings
......@@ -12365,19 +12365,19 @@ A double quote (@samp{"}) character.
@item \\
A backslash (@samp{\}) character.
@findex % (wildcard character)
@findex Wildcard character (%)
@findex % (wild card character)
@findex Wild card character (%)
@item \%
A @samp{%} character. This is used to search for literal instances of
@samp{%} in contexts where @samp{%} would otherwise be interpreted
as a wildcard character. @xref{String comparison functions}.
as a wild card character. @xref{String comparison functions}.
@findex _ (wildcard character)
@findex Wildcard character (_)
@findex _ (wild card character)
@findex Wild card character (_)
@item \_
A @samp{_} character. This is used to search for literal instances of
@samp{_} in contexts where @samp{_} would otherwise be interpreted
as a wildcard character. @xref{String comparison functions}.
as a wild card character. @xref{String comparison functions}.
@end table
Note that if you use @samp{\%} or @samp{\_} in some string contexts, these
......@@ -12483,11 +12483,11 @@ as the equivalent floating-point number.
@tindex Hexadecimal values
@node Hexadecimal values, NULL values, Number syntax, Literals
@subsection Hexadecimal values
@subsection Hexadecimal Values
@strong{MySQL} supports hexadecimal values. In number context these acts
like an integer (64 bit precision). In string context these acts like a binary
string where each pair of hex digits is converted to a character.
@strong{MySQL} supports hexadecimal values. In number context these act
like an integer (64-bit precision). In string context these act like a binary
string where each pair of hex digits is converted to a character:
@example
mysql> SELECT 0xa+0
......@@ -12496,11 +12496,11 @@ mysql> select 0x5061756c;
-> Paul
@end example
Hexadecimal strings is often used by ODBC to give values for BLOB columns.
Hexadecimal strings are often used by ODBC to give values for BLOB columns.
@tindex NULL value
@node NULL values, Legal names, Hexadecimal values, Literals
@subsection @code{NULL} values
@subsection @code{NULL} Values
The @code{NULL} value means ``no data'' and is different from values such
as @code{0} for numeric types or the empty string for string types.
......@@ -12511,35 +12511,35 @@ or export formats (@code{LOAD DATA INFILE}, @code{SELECT ... INTO OUTFILE}).
@xref{LOAD DATA, , @code{LOAD DATA}}.
@node Legal names, , NULL values, Literals
@subsection Database, table, index, column and alias names
@subsection Database, Table, Index, Column, and Alias Names
@menu
* Name case sensitivity:: Case sensitivity in names
@end menu
Database, table, index, column and alias names all follow the same rules in
@strong{MySQL}:
Database, table, index, column, and alias names all follow the same rules in
@strong{MySQL}.
@tindex Quoting of identifiers
@tindex `
@tindex "
Note that the rules changed starting with @strong{MySQL} 3.23.6 when we
introduced quoting of identifiers (database, table and column names)
Note that the rules changed starting with @strong{MySQL} Version 3.23.6 when we
introduced quoting of identifiers (database, table, and column names)
with @samp{`} (@samp{"} will also work to quote identifiers if you run
in ANSI mode).
@multitable @columnfractions .15 .15 .70
@item @strong{Identifier} @tab @strong{Max length} @tab @strong{Allowed characters}
@item Database @tab 64 @tab Any character that is allowed in a directory name except @code{/}.
@item Table @tab 64 @tab Any character that is allowed in file name, except @code{/} or @code{.}
@item Column @tab 64 @tab All characters
@item Alias @tab 255 @tab All characters
@item Database @tab 64 @tab Any character that is allowed in a directory name except @samp{/}.
@item Table @tab 64 @tab Any character that is allowed in a file name, except @samp{/} or @samp{.}.
@item Column @tab 64 @tab All characters.
@item Alias @tab 255 @tab All characters.
@end multitable
Note that in addition to the above, you can't have ASCII(0) or ASCII(255) in
an identifier.
Note that if the identifer is a restricted word or contains special character
Note that if the identifer is a restricted word or contains special characters
you must always quote it with @code{`} when you use it:
@example
......@@ -12580,7 +12580,7 @@ from whichever table used in the query contains a column of that name
@code{tbl_name} of the current database
@item @code{db_name.tbl_name.col_name} @tab Column @code{col_name} from table
@code{tbl_name} of the database @code{db_name}. This form is available in
@strong{MySQL} 3.22 or later.
@strong{MySQL} Version 3.22 or later.
@item
@code{`column_name`} @tab A column that is a keyword or contains special characters.
@end multitable
......@@ -12603,7 +12603,7 @@ database. This syntax is accepted for ODBC compatibility, because some ODBC
programs prefix table names with a @samp{.} character.
@node Name case sensitivity, , Legal names, Legal names
@subsubsection Case sensitivity in names
@subsubsection Case Sensitivity in Names
@cindex Database names, case sensitivity
@cindex Table names, case sensitivity
@cindex Column names, case sensitivity
......@@ -12616,10 +12616,10 @@ programs prefix table names with a @samp{.} character.
In @strong{MySQL}, databases and tables correspond to directories and files
within those directories. Consequently, the case sensitivity of the
underlying operating system determines the case sensitivity of database and
table names. This means database and table names are case sensitive in Unix
table names. This means database and table names are case sensitive in UNIX
and case insensitive in Windows.
@strong{Note:} Although database and table names are case insensitive for
@strong{NOTE:} Although database and table names are case insensitive for
Windows, you should not refer to a given database or table using different
cases within the same query. The following query would not work because it
refers to a table both as @code{my_table} and as @code{MY_TABLE}:
......@@ -12641,9 +12641,9 @@ mysql> SELECT col_name FROM tbl_name AS a
Aliases on columns are case insensitive.
@node Variables, Column types, Literals, Reference
@section User variables
@section User Variables
@strong{MySQL} supports thread specific variables with the
@strong{MySQL} supports thread-specific variables with the
@code{@@variablename} syntax. A variable name may consist of
alphanumeric characters from the current character set and also
@samp{_}, @samp{$}, and @samp{.} . The default character set is
......@@ -12652,7 +12652,7 @@ ISO-8859-1 Latin1; this may be changed with the
sets}.
Variables don't have to be initialized. They contain @code{NULL} by default
and can store an integer, real or string value. All variables for
and can store an integer, real, or string value. All variables for
a thread are automatically freed when the thread exits.
You can set a variable with the @code{SET} syntax:
......@@ -12683,10 +12683,10 @@ required, such as in the @code{LIMIT} clause of a @code{SELECT} statement,
or the @code{IGNORE number LINES} clause of a @code{LOAD DATA} statement.
@strong{NOTE:} In a @code{SELECT} statement, each expression is only
evaluated when it's sent to the client. This means that one can't
in the @code{HAVING}, @code{GROUP BY} or @code{ORDER BY} clause refer to an
expression that involves variables that are set in the @code{SELECT} part.
For example, the following statement will NOT work as expected:
evaluated when it's sent to the client. This means that in the @code{HAVING},
@code{GROUP BY}, or @code{ORDER BY} clause, you can't refer to an expression
that involves variables that are set in the @code{SELECT} part. For example,
the following statement will NOT work as expected:
@example
SELECT (@@aa:=id) AS a, (@@aa+3) AS b FROM table_name HAVING b=5;
......@@ -12696,7 +12696,7 @@ The reason is that @code{@@aa} will not contain the value of the current
row, but the value of @code{id} for the previous accepted row.
@node Column types, Functions, Variables, Reference
@section Column types
@section Column Types
@strong{MySQL} supports a number of column types, which may be grouped into
three categories: numeric types, date and time types, and string (character)
......@@ -12769,7 +12769,7 @@ A large integer. The signed range is @code{-9223372036854775808} to
@code{18446744073709551615}. Note that all arithmetic is done using
signed @code{BIGINT} or @code{DOUBLE} values, so you shouldn't use
unsigned big integers larger than @code{9223372036854775807} (63 bits)
except with bit functions! Note that @code{-}, @code{+} and @code{*}
except with bit functions! Note that @samp{-}, @samp{+}, and @samp{*}
will use @code{BIGINT} arithmetic when both arguments are @code{INTEGER}
values! This means that if you multiply two big integers (or results
from functions that return integers) you may get unexpected results if
......@@ -12780,14 +12780,13 @@ the result is larger than @code{9223372036854775807}.
@item FLOAT(precision) [ZEROFILL]
A floating-point number. Cannot be unsigned. @code{precision} can be
@code{<=24} for a single precision floating point number and between 25
and 53 for a double precision floating point number.
these types are like the @code{FLOAT} and @code{DOUBLE} types described
immediately below. @code{FLOAT(X)} have the same ranges as the
corresponding @code{FLOAT} and @code{DOUBLE} types, but the display
size and number of decimals is undefined.
In @strong{MySQL} 3.23, this is a true floating point value. In
@code{<=24} for a single-precision floating-point number and between 25
and 53 for a double-precision floating-point number. These types are like
the @code{FLOAT} and @code{DOUBLE} types described immediately below.
@code{FLOAT(X)} has the same range as the corresponding @code{FLOAT} and
@code{DOUBLE} types, but the display size and number of decimals is undefined.
In @strong{MySQL} Version 3.23, this is a true floating-point value. In
earlier @strong{MySQL} versions, @code{FLOAT(precision)} always has 2 decimals.
@cindex ODBC compatibility
......@@ -12800,10 +12799,10 @@ This syntax is provided for ODBC compatibility.
A small (single-precision) floating-point number. Cannot be unsigned.
Allowable values are @code{@w{-3.402823466E+38}} to
@code{@w{-1.175494351E-38}}, @code{0} and @code{@w{1.175494351E-38}} to
@code{@w{-1.175494351E-38}}, @code{0}, and @code{@w{1.175494351E-38}} to
@code{3.402823466E+38}. The M is the display width and D is the
number of decimals. @code{FLOAT} without an argument or with an argument of
<= 24 stands for a single-precision floating point number.
<= 24 stands for a single-precision floating-point number.
@tindex DOUBLE
@tindex FLOAT(precision)
......@@ -12811,11 +12810,11 @@ number of decimals. @code{FLOAT} without an argument or with an argument of
A normal-size (double-precision) floating-point number. Cannot be
unsigned. Allowable values are @code{@w{-1.7976931348623157E+308}} to
@code{@w{-2.2250738585072014E-308}}, @code{0} and
@code{@w{-2.2250738585072014E-308}}, @code{0}, and
@code{2.2250738585072014E-308} to @code{1.7976931348623157E+308}. The M
is the display width and D is the number of decimals. @code{DOUBLE}
without an argument or @code{FLOAT(X)} where 25 <= X <= 53 stands for a
double-precision floating point number.
double-precision floating-point number.
@tindex DOUBLE PRECISION
@tindex REAL
......@@ -12829,8 +12828,8 @@ These are synonyms for @code{DOUBLE}.
An unpacked floating-point number. Cannot be unsigned. Behaves like a
@code{CHAR} column: ``unpacked'' means the number is stored as a string,
using one character for each digit of the value. The decimal point,
and, for negative numbers, the @samp{-} sign is not counted in M. If
using one character for each digit of the value. The decimal point
and, for negative numbers, the @samp{-} sign, are not counted in M. If
@code{D} is 0, values will have no decimal point or fractional part.
The maximum range of @code{DECIMAL} values is the same as for
@code{DOUBLE}, but the actual range for a given @code{DECIMAL} column
......@@ -12838,8 +12837,8 @@ may be constrained by the choice of @code{M} and @code{D}.
If @code{D} is left out it's set to 0. If @code{M} is left out it's set to 10.
Note that in @strong{MySQL} 3.22 the @code{M} argument includes the sign
and the decimal point.
Note that in @strong{MySQL} Version 3.22 the @code{M} argument includes the
sign and the decimal point.
@tindex NUMERIC
@item NUMERIC(M,D) [ZEROFILL]
......@@ -12867,7 +12866,7 @@ to assign values to @code{DATETIME} columns using either strings or numbers.
A timestamp. The range is @code{'1970-01-01 00:00:00'} to sometime in the
year @code{2037}. @strong{MySQL} displays @code{TIMESTAMP} values in
@code{YYYYMMDDHHMMSS}, @code{YYMMDDHHMMSS}, @code{YYYYMMDD} or @code{YYMMDD}
@code{YYYYMMDDHHMMSS}, @code{YYMMDDHHMMSS}, @code{YYYYMMDD}, or @code{YYMMDD}
format, depending on whether @code{M} is @code{14} (or missing), @code{12},
@code{8} or @code{6}, but allows you to assign values to @code{TIMESTAMP}
columns using either strings or numbers. A @code{TIMESTAMP} column is useful
......@@ -12877,12 +12876,12 @@ recent operation if you don't give it a value yourself. You can also set it
to the current date and time by assigning it a @code{NULL} value. @xref{Date
and time types}.
A @code{TIMESTAMP} is always stored in 4 bytes; The @code{M} argument only
A @code{TIMESTAMP} is always stored in 4 bytes. The @code{M} argument only
affects how the @code{TIMESTAMP} column is displayed.
Note that @code{TIMESTAMP(X)} columns where X is 8 or 14 are reported to
be numbers while other @code{TIMESTAMP(X)} columns are reported to be
strings. This is just to ensure that one can reliable dump and restore
strings. This is just to ensure that one can reliably dump and restore
the table with these types!
@tindex TIME
......@@ -12896,12 +12895,12 @@ numbers.
@tindex YEAR
@item YEAR[(2|4)]
A year in 2- or 4- digit formats (default is 4-digit). The allowable values are
@code{1901} to @code{2155}, and @code{0000} in the 4 year format and
1970-2069 if you use the 2 digit format (70-69). @strong{MySQL} displays
@code{YEAR} values in @code{YYYY} format, but allows you to assign
values to @code{YEAR} columns using either strings or numbers.
(The @code{YEAR} type is new in @strong{MySQL} 3.22.)
A year in 2- or 4- digit formats (default is 4-digit). The allowable values
are @code{1901} to @code{2155}, and @code{0000} in the 4-digit year format,
and 1970-2069 if you use the 2-digit format (70-69). @strong{MySQL} displays
@code{YEAR} values in @code{YYYY} format, but allows you to assign values to
@code{YEAR} columns using either strings or numbers. (The @code{YEAR} type is
new in @strong{MySQL} Version 3.22.)
@tindex NATIONAL CHAR
@tindex NCHAR
......@@ -12917,7 +12916,7 @@ default character set unless the @code{BINARY} keyword is given.
@code{NATIONAL CHAR} (short form @code{NCHAR}) is the ANSI SQL way to
define that a CHAR column should use the default CHARACTER set. This is
default in @strong{MySQL}.
the default in @strong{MySQL}.
@code{CHAR} is a shorthand for @code{CHARACTER}.
......@@ -12934,11 +12933,11 @@ as @code{NOT NULL}, will only occupy one bit and can only take 2 values:
@tindex VARCHAR
@item [NATIONAL] VARCHAR(M) [BINARY]
A variable-length string. Note:
Trailing spaces are removed when the value is stored (this differs from the
ANSI SQL specification). The range of @code{M} is 1 to 255 characters.
@code{VARCHAR} values are sorted and compared in case-insensitive fashion
unless the @code{BINARY} keyword is given. @xref{Silent column changes}.
A variable-length string. @strong{NOTE:} Trailing spaces are removed when
the value is stored (this differs from the ANSI SQL specification). The range
of @code{M} is 1 to 255 characters. @code{VARCHAR} values are sorted and
compared in case-insensitive fashion unless the @code{BINARY} keyword is
given. @xref{Silent column changes}.
@code{VARCHAR} is a shorthand for @code{CHARACTER VARYING}.
......@@ -13003,14 +13002,14 @@ be chosen from the list of values @code{'value1'}, @code{'value2'},
@cindex Storage requirements
@node Storage requirements, Numeric types, Column types, Column types
@subsection Column type storage requirements
@subsection Column Type Storage Requirements
The storage requirements for each of the column types supported by
@strong{MySQL} are listed below by category.
@subheading Numeric types
@multitable @columnfractions .35 .65
@multitable @columnfractions .5 .5
@item @strong{Column type} @tab @strong{Storage required}
@item @code{TINYINT} @tab 1 byte
@item @code{SMALLINT} @tab 2 bytes
......@@ -13029,7 +13028,7 @@ The storage requirements for each of the column types supported by
@subheading Date and time types
@multitable @columnfractions .35 .65
@multitable @columnfractions .5 .5
@item @strong{Column type} @tab @strong{Storage required}
@item @code{DATE} @tab 3 bytes
@item @code{DATETIME} @tab 8 bytes
......@@ -13040,7 +13039,7 @@ The storage requirements for each of the column types supported by
@subheading String types
@multitable @columnfractions .35 .65
@multitable @columnfractions .5 .5
@item @strong{Column type} @tab @strong{Storage required}
@item @code{CHAR(M)} @tab @code{M} bytes, @code{1 <= M <= 255}
@item @code{VARCHAR(M)} @tab @code{L}+1 bytes, where @code{L <= M} and
......@@ -13068,26 +13067,26 @@ storage required is the length of the string (@code{L}), plus 1 byte to
record the length of the string. For the string @code{'abcd'}, @code{L} is 4
and the storage requirement is 5 bytes.
The @code{BLOB} and @code{TEXT} types require 1, 2, 3 or 4 bytes to record
The @code{BLOB} and @code{TEXT} types require 1, 2, 3, or 4 bytes to record
the length of the column value, depending on the maximum possible length of
the type.
If a table includes any variable-length column types, the record format will
also be variable-length. Note that when a table is created, @strong{MySQL}
may under certain conditions change a column from a variable-length type to a
may, under certain conditions, change a column from a variable-length type to a
fixed-length type, or vice-versa. @xref{Silent column changes}.
The size of an @code{ENUM} object is determined by the number of different
enumeration values. 1 byte is used for enumerations with up to 255 possible
values. 2 bytes are used for enumerations with up to 65535 values.
enumeration values. One byte is used for enumerations with up to 255 possible
values. Two bytes are used for enumerations with up to 65535 values.
The size of a @code{SET} object is determined by the number of different
set members. If the set size is @code{N}, the object occupies @code{(N+7)/8}
bytes, rounded up to 1, 2, 3, 4 or 8 bytes. A @code{SET} can have a maximum
bytes, rounded up to 1, 2, 3, 4, or 8 bytes. A @code{SET} can have a maximum
of 64 members.
@node Numeric types, Date and time types, Storage requirements, Column types
@subsection Numeric types
@subsection Numeric Types
@strong{MySQL} supports all of the ANSI/ISO SQL92 numeric types. These
types include the exact numeric data types (@code{NUMERIC},
......@@ -13109,10 +13108,10 @@ example:
@end example
In this example, @code{9} (@code{precision}) represents the number of
significant decimal digits which will be stored for values, and
@code{2} (@code{scale}) represents the number of digits which will be
significant decimal digits that will be stored for values, and
@code{2} (@code{scale}) represents the number of digits that will be
stored following the decimal point. In this case, therefore, the range
of values which can be stored in the @code{salary} column is from
of values that can be stored in the @code{salary} column is from
@code{-9999999.99} to @code{9999999.99}. In ANSI/ISO SQL92, the syntax
@code{DECIMAL(p)} is equivalent to @code{DECIMAL(p,0)}. Similarly, the
syntax @code{DECIMAL} is equivalent to @code{DECIMAL(p,0)}, where the
......@@ -13125,7 +13124,7 @@ the ability to control both precision and scale explicitly.
@code{DECIMAL} and @code{NUMERIC} values are stored as strings, rather
than as binary floating point numbers, in order to preserve the decimal
precision of those values. One character is used for each digit of the
value, the decimal point (if @code{scale} > 0) and the @samp{-} sign
value, the decimal point (if @code{scale} > 0), and the @samp{-} sign
(for negative numbers). If @code{scale} is 0, @code{DECIMAL} and
@code{NUMERIC} values contain no decimal point or fractional part.
......@@ -13149,16 +13148,16 @@ of an integral value in parentheses following the base keyword for the
type (for example, @code{INT(4)}). This optional width specification is
used to left-pad the display of values whose width is less than the
width specified for the column, but does not constrain the range of
values which can be stored in the column, nor the number of digits which
values which can be stored in the column, nor the number of digits that
will be displayed for values whose width exceeds that specified for the
column. When used in conjunction with the optional extension attribute
@code{ZEROFILL} the default padding of spaces is replaced with zeroes.
@code{ZEROFILL}, the default padding of spaces is replaced with zeroes.
For example, for a column declared as @code{INT(5) ZEROFILL}, a value
of @code{4} is retrieved as @code{00004}. Note that if you store larger
values than the display width in an integral column, you may experience
values than the display width in an integer column, you may experience
problems when @strong{MySQL} generates temporary tables for some
complicated joins as in these case @strong{MySQL} trust that the data
did fit into the original column width.
complicated joins, as in these cases @strong{MySQL} will trust that the
data did fit into the original column width.
All integral types can have an optional (non-standard) attribute
@code{UNSIGNED}. Unsigned values can be used when you want to allow
......@@ -13188,7 +13187,7 @@ standard, @strong{MySQL} recognizes @code{DOUBLE} as a synonym for the
@code{DOUBLE PRECISION} type. In contrast with the standard's
requirement that the precision for @code{REAL} be smaller than that used
for @code{DOUBLE PRECISION}, @strong{MySQL} implements both as 8-byte
double-precision floating point values (when not running in ``Ansi mode'').
double-precision floating-point values (when not running in ``Ansi mode'').
For maximum portability, code requiring storage of approximate numeric
data values should use @code{FLOAT} or @code{DOUBLE PRECISION} with no
specification of precision or number of decimal points.
......@@ -13209,13 +13208,13 @@ If you try to store @code{-9999999999} and @code{9999999999},
the values stored in the column become @code{0} and @code{4294967296}.
Conversions that occur due to clipping are reported as ``warnings'' for
@code{ALTER TABLE}, @code{LOAD DATA INFILE}, @code{UPDATE} and
@code{ALTER TABLE}, @code{LOAD DATA INFILE}, @code{UPDATE}, and
multi-row @code{INSERT} statements.
@cindex Types, Date and Time
@cindex Date and Time types
@node Date and time types, String types, Numeric types, Column types
@subsection Date and time types
@subsection Date and Time Types
@menu
* Y2K issues:: Y2K issues and date types
......@@ -13225,7 +13224,7 @@ multi-row @code{INSERT} statements.
@end menu
The date and time types are @code{DATETIME}, @code{DATE},
@code{TIMESTAMP}, @code{TIME} and @code{YEAR}. Each of these has a
@code{TIMESTAMP}, @code{TIME}, and @code{YEAR}. Each of these has a
range of legal values, as well as a ``zero'' value that is used when you
specify a really illegal value. Note that @strong{MySQL} allows you to store
certain 'not strictly' legal date values, for example @code{1999-11-31}.
......@@ -13235,11 +13234,11 @@ date checking 'fast', @strong{MySQL} only checks that the month is in
the range of 0-12 and the day is in the range of 0-31. The above ranges
are defined this way because @strong{MySQL} allows you to store, in a
@code{DATE} or @code{DATETIME} column, dates where the day or month-day
are zero. This is extremely useful for applications that need to store
is zero. This is extremely useful for applications that need to store
a birth-date for which you don't know the exact date. In this case you
simply store the date like @code{1999-00-00} or @code{1999-01-00}. (You
can of course not expect to get a correct value from functions like
@code{DATE_SUB()} or @code{DATE_ADD} for dates like these).
cannot expect to get a correct value from functions like @code{DATE_SUB()}
or @code{DATE_ADD} for dates like these.)
Here are some general considerations to keep in mind when working
with date and time types:
......@@ -13248,18 +13247,18 @@ with date and time types:
@item
@strong{MySQL} retrieves values for a given date or time type in a standard
format, but it attempts to interpret a variety of formats for values that
you supply (e.g., when you specify a value to be assigned to or compared to a
date or time type). Nevertheless, only the formats described in the
following sections are supported. It is expected that you will supply legal
values, and unpredictable results may occur if you use values in other
you supply (for example, when you specify a value to be assigned to or
compared to a date or time type). Nevertheless, only the formats described
in the following sections are supported. It is expected that you will supply
legal values, and unpredictable results may occur if you use values in other
formats.
@item
Although @strong{MySQL} tries to interpret values in several formats, it
always expects the year part of date values to be leftmost. Dates must be
given in year-month-day order (e.g., @code{'98-09-04'}), rather than in the
month-day-year or day-month-year orders commonly used elsewhere (e.g.,
@code{'09-04-98'}, @code{'04-09-98'}).
given in year-month-day order (for example, @code{'98-09-04'}), rather than
in the month-day-year or day-month-year orders commonly used elsewhere (for
example, @code{'09-04-98'}, @code{'04-09-98'}).
@item
@strong{MySQL} automatically converts a date or time type value to a number
......@@ -13267,7 +13266,7 @@ if the value is used in a numeric context, and vice versa.
@item
When @strong{MySQL} encounters a value for a date or time type that is
out of range or otherwise illegal for the type (see start of this
out of range or otherwise illegal for the type (see the start of this
section), it converts the value to the ``zero'' value for that type.
(The exception is that out-of-range @code{TIME} values are clipped to
the appropriate endpoint of the @code{TIME} range.) The table below
......@@ -13289,13 +13288,13 @@ using the values @code{'0'} or @code{0}, which are easier to write.
@item
``Zero'' date or time values used through @strong{MyODBC} are converted
automatically to @code{NULL} in @strong{MyODBC} 2.50.12 and above, because
ODBC can't handle such values.
automatically to @code{NULL} in @strong{MyODBC} Version 2.50.12 and above,
because ODBC can't handle such values.
@end itemize
@cindex Year 2000 issues
@node Y2K issues, DATETIME, Date and time types, Date and time types
@subsubsection Y2K issues and date types
@subsubsection Y2K Issues and Date Types
@strong{MySQL} itself is Y2K-safe (@pxref{Year 2000 compliance}),
but input values presented to @strong{MySQL} may not be. Any input
......@@ -13303,7 +13302,7 @@ containing 2-digit year values is ambiguous, because the century is unknown.
Such values must be interpreted into 4-digit form because @strong{MySQL} stores
years internally using four digits.
For @code{DATETIME}, @code{DATE}, @code{TIMESTAMP} and @code{YEAR} types,
For @code{DATETIME}, @code{DATE}, @code{TIMESTAMP}, and @code{YEAR} types,
@strong{MySQL} interprets dates with ambiguous year values using the
following rules:
......@@ -13320,22 +13319,22 @@ data mean. If the heuristics used by @strong{MySQL} don't produce the
correct values, you should provide unambiguous input containing 4-digit
year values.
@code{ORDER BY} will sort 2 digit @code{YEAR/DATE/DATETIME} types properly.
@code{ORDER BY} will sort 2-digit @code{YEAR/DATE/DATETIME} types properly.
Note also that some functions like @code{MIN()} and @code{MAX()} will convert a
@code{TIMESTAMP/DATE} to a number. This means that a timestamp with a 2
digit year will not work properly with these functions. The fix in this
case is to convert the @code{TIMESTAMP/DATE} to 4 digit year format or
@code{TIMESTAMP/DATE} to a number. This means that a timestamp with a
2-digit year will not work properly with these functions. The fix in this
case is to convert the @code{TIMESTAMP/DATE} to 4-digit year format or
use something like @code{MIN(DATE_ADD(timestamp,INTERVAL 0 DAYS))}.
@tindex DATETIME
@tindex DATE
@tindex TIMESTAMP
@node DATETIME, TIME, Y2K issues, Date and time types
@subsubsection The @code{DATETIME}, @code{DATE} and @code{TIMESTAMP} types
@subsubsection The @code{DATETIME}, @code{DATE}, and @code{TIMESTAMP} Types
The @code{DATETIME}, @code{DATE} and @code{TIMESTAMP} types are related.
This section describes their characteristics, how they are similar and how
The @code{DATETIME}, @code{DATE}, and @code{TIMESTAMP} types are related.
This section describes their characteristics, how they are similar, and how
they differ.
The @code{DATETIME} type is used when you need values that contain both date
......@@ -13373,7 +13372,7 @@ You explicitly set the @code{TIMESTAMP} column to @code{NULL}.
@end itemize
@code{TIMESTAMP} columns other than the first may also be set to the current
date and time. Just set the column to @code{NULL}, or to @code{NOW()}.
date and time. Just set the column to @code{NULL} or to @code{NOW()}.
You can set any @code{TIMESTAMP} column to a value different than the current
date and time by setting it explicitly to the desired value. This is true
......@@ -13422,7 +13421,7 @@ specify an arbitrary display size at table creation time, but values of 0 or
greater than 14 are coerced to 14. Odd-valued sizes in the range from 1 to
13 are coerced to the next higher even number.
You can specify @code{DATETIME}, @code{DATE} and @code{TIMESTAMP} values using
You can specify @code{DATETIME}, @code{DATE}, and @code{TIMESTAMP} values using
any of a common set of formats:
@itemize @bullet
......@@ -13431,13 +13430,13 @@ As a string in either @code{'YYYY-MM-DD HH:MM:SS'} or @code{'YY-MM-DD
HH:MM:SS'} format. A ``relaxed'' syntax is allowed---any punctuation
character may be used as the delimiter between date parts or time parts.
For example, @code{'98-12-31 11:30:45'}, @code{'98.12.31 11+30+45'},
@code{'98/12/31 11*30*45'} and @code{'98@@12@@31 11^30^45'} are
@code{'98/12/31 11*30*45'}, and @code{'98@@12@@31 11^30^45'} are
equivalent.
@item
As a string in either @code{'YYYY-MM-DD'} or @code{'YY-MM-DD'} format.
A ``relaxed'' syntax is allowed here, too. For example, @code{'98-12-31'},
@code{'98.12.31'}, @code{'98/12/31'} and @code{'98@@12@@31'} are
@code{'98.12.31'}, @code{'98/12/31'}, and @code{'98@@12@@31'} are
equivalent.
@item
......@@ -13468,23 +13467,23 @@ format, provided that the number makes sense as a date. For example,
@item
As the result of a function that returns a value that is acceptable
in a @code{DATETIME}, @code{DATE} or @code{TIMESTAMP} context, such as
in a @code{DATETIME}, @code{DATE}, or @code{TIMESTAMP} context, such as
@code{NOW()} or @code{CURRENT_DATE}.
@end itemize
Illegal @code{DATETIME}, @code{DATE} or @code{TIMESTAMP} values are converted
Illegal @code{DATETIME}, @code{DATE}, or @code{TIMESTAMP} values are converted
to the ``zero'' value of the appropriate type (@code{'0000-00-00 00:00:00'},
@code{'0000-00-00'} or @code{00000000000000}).
@code{'0000-00-00'}, or @code{00000000000000}).
For values specified as strings that include date part delimiters, it is not
necessary to specify two digits for month or day values that are less than
@code{10}. @code{'1979-6-9'} is the same as @code{'1979-06-09'}. Similarly,
for values specified as strings that include time part delimiters, it is not
necessary to specify two digits for hour, month or second values that are
necessary to specify two digits for hour, month, or second values that are
less than @code{10}. @code{'1979-10-30 1:2:3'} is the same as
@code{'1979-10-30 01:02:03'}.
Values specified as numbers should be 6, 8, 12 or 14 digits long. If the
Values specified as numbers should be 6, 8, 12, or 14 digits long. If the
number is 8 or 14 digits long, it is assumed to be in @code{YYYYMMDD} or
@code{YYYYMMDDHHMMSS} format and that the year is given by the first 4
digits. If the number is 6 or 12 digits long, it is assumed to be in
......@@ -13496,7 +13495,7 @@ Values specified as non-delimited strings are interpreted using their length
as given. If the string is 8 or 14 characters long, the year is assumed to
be given by the first 4 characters. Otherwise the year is assumed to be
given by the first 2 characters. The string is interpreted from left to
right to find year, month, day, hour, minute and second values, for as many
right to find year, month, day, hour, minute, and second values, for as many
parts as are present in the string. This means you should not use strings
that have fewer than 6 characters. For example, if you specify @code{'9903'},
thinking that will represent March, 1999, you will find that @strong{MySQL}
......@@ -13551,7 +13550,7 @@ object, the time part of the resulting value is deleted, because the
@code{DATE} type stores no time information.
@item
Remember that although @code{DATETIME}, @code{DATE} and @code{TIMESTAMP}
Remember that although @code{DATETIME}, @code{DATE}, and @code{TIMESTAMP}
values all can be specified using the same set of formats, the types do not
all have the same range of values. For example, @code{TIMESTAMP} values
cannot be earlier than @code{1970} or later than @code{2037}. This means
......@@ -13587,7 +13586,7 @@ Year values in the range @code{70-99} are converted to @code{1970-1999}.
@tindex TIME
@node TIME, YEAR, DATETIME, Date and time types
@subsubsection The @code{TIME} type
@subsubsection The @code{TIME} Type
@strong{MySQL} retrieves and displays @code{TIME} values in @code{'HH:MM:SS'}
format (or @code{'HHH:MM:SS'} format for large hours values). @code{TIME}
......@@ -13627,15 +13626,15 @@ in a @code{TIME} context, such as @code{CURRENT_TIME}.
@end itemize
For @code{TIME} values specified as strings that include a time part
delimiter, it is not necessary to specify two digits for hours, minutes or
delimiter, it is not necessary to specify two digits for hours, minutes, or
seconds values that are less than @code{10}. @code{'8:3:2'} is the same as
@code{'08:03:02'}.
Be careful about assigning ``short'' @code{TIME} values to a @code{TIME}
column. @strong{MySQL} interprets values using the assumption that the
rightmost digits represent seconds. (@strong{MySQL} interprets @code{TIME}
values as elapsed time, rather than as time of day.) For example, you might
think of @code{'11:12'}, @code{'1112'} and @code{1112} as meaning
values as elapsed time rather than as time of day.) For example, you might
think of @code{'11:12'}, @code{'1112'}, and @code{1112} as meaning
@code{'11:12:00'} (12 minutes after 11 o'clock), but @strong{MySQL}
interprets them as @code{'00:11:12'} (11 minutes, 12 seconds). Similarly,
@code{'12'} and @code{12} are interpreted as @code{'00:00:12'}.
......@@ -13653,7 +13652,7 @@ original value was specified as @code{'00:00:00'} or whether it was illegal.
@tindex YEAR
@node YEAR, , TIME, Date and time types
@subsubsection The @code{YEAR} type
@subsubsection The @code{YEAR} Type
The @code{YEAR} type is a 1-byte type used for representing years.
......@@ -13693,10 +13692,10 @@ in a @code{YEAR} context, such as @code{NOW()}.
Illegal @code{YEAR} values are converted to @code{0000}.
@node String types, Choosing types, Date and time types, Column types
@subsection String types
@subsection String Types
The string types are @code{CHAR}, @code{VARCHAR}, @code{BLOB}, @code{TEXT},
@code{ENUM} and @code{SET}.
@code{ENUM}, and @code{SET}.
@tindex CHAR
@tindex VARCHAR
......@@ -13708,14 +13707,14 @@ The string types are @code{CHAR}, @code{VARCHAR}, @code{BLOB}, @code{TEXT},
@end menu
@node CHAR, BLOB, String types, String types
@subsubsection The @code{CHAR} and @code{VARCHAR} types
@subsubsection The @code{CHAR} and @code{VARCHAR} Types
The @code{CHAR} and @code{VARCHAR} types are similar, but differ in the
way they are stored and retrieved.
The length of a @code{CHAR} column is fixed to the length that you declare
when you create the table. The length can be any value between 1 and 255.
(As of @strong{MySQL} 3.23, the length of @code{CHAR} may be 0 to 255.)
(As of @strong{MySQL} Version 3.23, the length of @code{CHAR} may be 0 to 255.)
When @code{CHAR} values are stored, they are right-padded with spaces to the
specified length. When @code{CHAR} values are retrieved, trailing spaces are
removed.
......@@ -13756,7 +13755,7 @@ when the table was created. The @code{BINARY} attribute means that column
values are sorted and compared in case-sensitive fashion according to the
ASCII order of the machine where the @strong{MySQL} server is running.
The @code{BINARY} attribute is ``sticky''. This means that if a column marked
The @code{BINARY} attribute is sticky. This means that if a column marked
@code{BINARY} is used in an expression, the whole expression is compared as a
@code{BINARY} value.
......@@ -13767,15 +13766,15 @@ column at table creation time.
@tindex BLOB
@tindex TEXT
@node BLOB, ENUM, CHAR, String types
@subsubsection The @code{BLOB} and @code{TEXT} types
@subsubsection The @code{BLOB} and @code{TEXT} Types
A @code{BLOB} is a binary large object that can hold a variable amount of
data. The four @code{BLOB} types @code{TINYBLOB}, @code{BLOB},
@code{MEDIUMBLOB} and @code{LONGBLOB} differ only in the maximum length of
@code{MEDIUMBLOB}, and @code{LONGBLOB} differ only in the maximum length of
the values they can hold.
@xref{Storage requirements}.
The four @code{TEXT} types @code{TINYTEXT}, @code{TEXT}, @code{MEDIUMTEXT}
The four @code{TEXT} types @code{TINYTEXT}, @code{TEXT}, @code{MEDIUMTEXT},
and @code{LONGTEXT} correspond to the four @code{BLOB} types and have the
same maximum lengths and storage requirements. The only difference between
@code{BLOB} and @code{TEXT} types is that sorting and comparison is performed
......@@ -13793,7 +13792,7 @@ column that can be as big as you like. Similarly, you can regard a
@itemize @bullet
@item
You can have indexes on @code{BLOB} and @code{TEXT} columns with
@strong{MySQL} versions 3.23.2 and newer. Older versions of
@strong{MySQL} Version 3.23.2 and newer. Older versions of
@strong{MySQL} did not support this.
@item
......@@ -13847,12 +13846,12 @@ do so on both the server and client ends. @xref{Server parameters}.
@end itemize
Note that each @code{BLOB} or @code{TEXT} value is represented internally by
a separately-allocated object. This is in contrast to all other column types,
a separately allocated object. This is in contrast to all other column types,
for which storage is allocated once per column when the table is opened.
@tindex ENUM
@node ENUM, SET, BLOB, String types
@subsubsection The @code{ENUM} type
@subsubsection The @code{ENUM} Type
An @code{ENUM} is a string object whose value normally is chosen from a list
of allowed values that are enumerated explicitly in the column specification
......@@ -13914,7 +13913,7 @@ values that were used to specify the allowable values at table creation time.
If you retrieve an @code{ENUM} in a numeric context, the column value's index
is returned. If you store a number into an @code{ENUM}, the number is
treated as an index, and the the value stored is the enumeration member with
treated as an index, and the value stored is the enumeration member with
that index. (However, this will not work with @code{LOAD DATA}, which treats
all input as strings.)
......@@ -13932,7 +13931,7 @@ the @code{ENUM} definition in the second column.
@tindex SET
@node SET, , ENUM, String types
@subsubsection The @code{SET} type
@subsubsection The @code{SET} Type
A @code{SET} is a string object that can have zero or more values, each of
which must be chosen from a list of allowed values specified when the table
......@@ -13980,7 +13979,7 @@ does not matter how many times a given element is listed in the value.
When the value is retrieved later, each element in the value will appear
once, with elements listed according to the order in which they were
specified at table creation time. For example, if a column is specified as
@code{SET("a","b","c","d")}, then @code{"a,d"}, @code{"d,a"} and
@code{SET("a","b","c","d")}, then @code{"a,d"}, @code{"d,a"}, and
@code{"d,a,a,d,d"} will all appear as @code{"a,d"} when retrieved.
@code{SET} values are sorted numerically. @code{NULL} values sort before
......@@ -14011,7 +14010,7 @@ the @code{SET} definition in the second column.
@cindex Types, choosing
@cindex Choosing types
@node Choosing types, Indexes, String types, Column types
@subsection Choosing the right type for a column
@subsection Choosing the Right Type for a Column
For the most efficient use of storage, try to use the most precise type in
all cases. For example, if an integer column will be used for values in the
......@@ -14030,7 +14029,7 @@ and convert results back to floating-point values only when necessary.
@cindex Indexes
@cindex Keys
@node Indexes, Multiple-column indexes, Choosing types, Column types
@subsection Column indexes
@subsection Column Indexes
All @strong{MySQL} column types can be indexed. Use of indexes on the
relevant columns is the best way to improve the performance of @code{SELECT}
......@@ -14058,17 +14057,17 @@ mysql> CREATE TABLE test (
@end example
For @code{BLOB} and @code{TEXT} columns, you must index a prefix of the
column, you cannot index the entire thing.
column. You cannot index the entire column.
In @strong{MySQL} 3.23.23 or later, you can also create special
In @strong{MySQL} Version 3.23.23 or later, you can also create special
@strong{FULLTEXT} indexes. They are used for full-text search. Only the
@code{MyISAM} table type supports @code{FULLTEXT} indexes. They can be created
only from @code{VARCHAR} and @code{TEXT} columns.
Indexing always happens over the entire column, partial indexing is not
supported. See @ref{MySQL full-text search} for details of operation.
@code{MyISAM} table type supports @code{FULLTEXT} indexes. They can be
created only from @code{VARCHAR} and @code{TEXT} columns.
Indexing always happens over the entire column and partial indexing is not
supported. See @ref{MySQL full-text search} for details.
@node Multiple-column indexes, Other-vendor column types, Indexes, Column types
@subsection Multiple-column indexes
@subsection Multiple-column Indexes
@strong{MySQL} can create indexes on multiple columns. An index may
consist of up to 15 columns. (On @code{CHAR} and @code{VARCHAR} columns you
......@@ -14126,7 +14125,7 @@ indexes}.
@cindex Type portability
@node Other-vendor column types, , Multiple-column indexes, Column types
@subsection Using column types from other database engines
@subsection Using Column Types from Other Database Engines
To make it easier to use code written for SQL implementations from other
vendors, @strong{MySQL} maps column types as shown in the table below. These
......@@ -14157,7 +14156,7 @@ statement, @strong{MySQL} reports the table structure using the equivalent
@cindex Functions for @code{SELECT} and @code{WHERE} clauses
@node Functions, CREATE DATABASE, Column types, Reference
@section Functions for use in @code{SELECT} and @code{WHERE} clauses
@section Functions for Use in @code{SELECT} and @code{WHERE} Clauses
A @code{select_expression} or @code{where_definition} in a SQL statement
can consist of any expression using the functions described below.
......@@ -14166,7 +14165,7 @@ An expression that contains @code{NULL} always produces a @code{NULL} value
unless otherwise indicated in the documentation for the operators and
functions involved in the expression.
@strong{Note:} There must be no whitespace between a function name and the
@strong{NOTE:} There must be no whitespace between a function name and the
parenthesis following it. This helps the @strong{MySQL} parser distinguish
between function calls and references to tables or columns that happen to
have the same name as a function. Spaces around arguments are permitted,
......@@ -14187,7 +14186,7 @@ mysql> select MOD(29,9);
+-----------+
@end example
Is displayed like this:
is displayed like this:
@example
mysql> select MOD(29,9);
......@@ -14211,14 +14210,14 @@ mysql> select MOD(29,9);
@end menu
@node Grouping functions, Arithmetic functions, Functions, Functions
@subsection Grouping functions
@subsection Grouping Functions
@cindex Grouping of expressions
@table @code
@findex () (parentheses)
@findex parentheses ( and )
@item ( ... )
Parentheses. Use these to force the order of evaluation in an expression.
Parentheses. Use these to force the order of evaluation in an expression:
@example
mysql> select 1+2*3;
-> 7
......@@ -14228,10 +14227,10 @@ mysql> select (1+2)*3;
@end table
@node Arithmetic functions, Bit functions, Grouping functions, Functions
@subsection Normal arithmetic operations
@subsection Normal Arithmetic Operations
The usual arithmetic operators are available. Note that in the case of
@code{-}, @code{+} and @code{*}, the result is calculated with @code{BIGINT}
@samp{-}, @samp{+}, and @samp{*}, the result is calculated with @code{BIGINT}
(64-bit) precision if both arguments are integers!
@cindex Arithmetic expressions
......@@ -14239,7 +14238,7 @@ The usual arithmetic operators are available. Note that in the case of
@findex + (addition)
@findex addition (+)
@item +
Addition
Addition:
@example
mysql> select 3+5;
-> 8
......@@ -14248,7 +14247,7 @@ mysql> select 3+5;
@findex - (subtraction)
@findex subtraction (-)
@item -
Subtraction
Subtraction:
@example
mysql> select 3-5;
-> -2
......@@ -14257,7 +14256,7 @@ mysql> select 3-5;
@findex * (multiplication)
@findex multiplication (*)
@item *
Multiplication
Multiplication:
@example
mysql> select 3*5;
-> 15
......@@ -14273,7 +14272,7 @@ multiplication exceeds the 64-bit range of @code{BIGINT} calculations.
@findex / (division)
@findex division (/)
@item /
Division
Division:
@example
mysql> select 3/5;
-> 0.60
......@@ -14295,7 +14294,7 @@ in a context where its result is converted to an integer!
@findex Functions, arithmetic
@findex Functions, bit
@node Bit functions, Logical functions, Arithmetic functions, Functions
@subsection Bit functions
@subsection Bit Functions
@strong{MySQL} uses @code{BIGINT} (64-bit) arithmetic for bit operations, so
these operators have a maximum range of 64 bits.
......@@ -14304,7 +14303,7 @@ these operators have a maximum range of 64 bits.
@findex | (bitwise OR)
@findex OR, bitwise
@item |
Bitwise OR
Bitwise OR:
@example
mysql> select 29 | 15;
-> 31
......@@ -14313,7 +14312,7 @@ mysql> select 29 | 15;
@findex & (bitwise AND)
@findex AND, bitwise
@item &
Bitwise AND
Bitwise AND:
@example
mysql> select 29 & 15;
-> 13
......@@ -14321,7 +14320,7 @@ mysql> select 29 & 15;
@findex << (left shift)
@item <<
Shifts a longlong (@code{BIGINT}) number to the left.
Shifts a longlong (@code{BIGINT}) number to the left:
@example
mysql> select 1 << 2
-> 4
......@@ -14329,7 +14328,7 @@ mysql> select 1 << 2
@findex >> (right shift)
@item >>
Shifts a longlong (@code{BIGINT}) number to the right.
Shifts a longlong (@code{BIGINT}) number to the right:
@example
mysql> select 4 >> 2
-> 1
......@@ -14337,7 +14336,7 @@ mysql> select 4 >> 2
@findex ~
@item ~
Invert all bits.
Invert all bits:
@example
mysql> select 5 & ~1
-> 4
......@@ -14345,7 +14344,7 @@ mysql> select 5 & ~1
@findex BIT_COUNT()
@item BIT_COUNT(N)
Returns the number of bits that are set in the argument @code{N}.
Returns the number of bits that are set in the argument @code{N}:
@example
mysql> select BIT_COUNT(29);
-> 4
......@@ -14355,9 +14354,9 @@ mysql> select BIT_COUNT(29);
@findex Logical functions
@findex Functions, logical
@node Logical functions, Comparison functions, Bit functions, Functions
@subsection Logical operations
@subsection Logical Operations
All logical functions return @code{1} (TRUE) or @code{0} (FALSE).
All logical functions return @code{1} (TRUE) or @code{0} (FALSE):
@table @code
@findex NOT, logical
......@@ -14366,7 +14365,7 @@ All logical functions return @code{1} (TRUE) or @code{0} (FALSE).
@itemx !
Logical NOT. Returns @code{1} if the argument is @code{0}, otherwise returns
@code{0}.
Exception: @code{NOT NULL} returns @code{NULL}.
Exception: @code{NOT NULL} returns @code{NULL}:
@example
mysql> select NOT 1;
-> 0
......@@ -14385,7 +14384,7 @@ the same way as @code{(!1)+1}.
@item OR
@itemx ||
Logical OR. Returns @code{1} if either argument is not @code{0} and not
@code{NULL}.
@code{NULL}:
@example
mysql> select 1 || 0;
-> 1
......@@ -14401,7 +14400,7 @@ mysql> select 1 || NULL;
@item AND
@itemx &&
Logical AND. Returns @code{0} if either argument is @code{0} or @code{NULL},
otherwise returns @code{1}.
otherwise returns @code{1}:
@example
mysql> select 1 && NULL;
-> 0
......@@ -14414,9 +14413,9 @@ mysql> select 1 && 0;
@cindex Type conversions
@findex Comparison operators
@node Comparison functions, String comparison functions, Logical functions, Functions
@subsection Comparison operators
@subsection Comparison Operators
Comparison operations result in a value of @code{1} (TRUE), @code{0} (FALSE)
Comparison operations result in a value of @code{1} (TRUE), @code{0} (FALSE),
or @code{NULL}. These functions work for both numbers and strings. Strings
are automatically converted to numbers and numbers to strings as needed (as
in Perl).
......@@ -14474,7 +14473,7 @@ mysql> SELECT 0 = 'x6';
@findex = (equal)
@findex equal (=)
@item =
Equal
Equal:
@example
mysql> select 1 = 0;
-> 0
......@@ -14494,7 +14493,7 @@ mysql> select '.01' = 0.01;
@findex not equal (!=)
@item <>
@itemx !=
Not equal
Not equal:
@example
mysql> select '.01' <> '0.01';
-> 1
......@@ -14507,7 +14506,7 @@ mysql> select 'zapp' <> 'zappp';
@findex <= (less than or equal)
@findex less than or equal (<=)
@item <=
Less than or equal
Less than or equal:
@example
mysql> select 0.1 <= 2;
-> 1
......@@ -14516,7 +14515,7 @@ mysql> select 0.1 <= 2;
@findex < (less than)
@findex less than (<)
@item <
Less than
Less than:
@example
mysql> select 2 <= 2;
-> 1
......@@ -14525,7 +14524,7 @@ mysql> select 2 <= 2;
@findex >= (greater than or equal)
@findex greater than or equal (>=)
@item >=
Greater than or equal
Greater than or equal:
@example
mysql> select 2 >= 2;
-> 1
......@@ -14534,7 +14533,7 @@ mysql> select 2 >= 2;
@findex > (greater than)
@findex greater than (>)
@item >
Greater than
Greater than:
@example
mysql> select 2 > 2;
-> 0
......@@ -14542,7 +14541,7 @@ mysql> select 2 > 2;
@findex <=> (Equal to)
@item <=>
Null safe equal
Null safe equal:
@example
mysql> select 1 <=> 1, NULL <=> NULL, 1 <=> NULL;
-> 1 1 0
......@@ -14552,7 +14551,7 @@ mysql> select 1 <=> 1, NULL <=> NULL, 1 <=> NULL;
@findex IS NOT NULL
@item IS NULL
@itemx IS NOT NULL
Test whether or not a value is or is not @code{NULL}
Test whether or not a value is or is not @code{NULL}:
@example
mysql> select 1 IS NULL, 0 IS NULL, NULL IS NULL:
-> 0 0 1
......@@ -14571,9 +14570,9 @@ comparison is performed as follows:
@itemize @bullet
@item
If @code{expr} is a @code{TIMESTAMP}, @code{DATE} or @code{DATETIME}
column, min and max are formatted to the same format if they
are constants.
If @code{expr} is a @code{TIMESTAMP}, @code{DATE}, or @code{DATETIME}
column, @code{MIN()} and @code{MAX()} are formatted to the same format if
they are constants.
@item
If @code{expr} is a case-insensitive string expression, a case-insensitive
string comparison is done.
......@@ -14605,7 +14604,7 @@ evaluated according to the type of @code{expr} and sorted. The search for the
item is then done using a binary search. This means @code{IN} is very quick
if the @code{IN} value list consists entirely of constants. If @code{expr}
is a case-sensitive string expression, the string comparison is performed in
case-sensitive fashion.
case-sensitive fashion:
@example
mysql> select 2 IN (0,3,5,'wefwf');
......@@ -14621,7 +14620,7 @@ Same as @code{NOT (expr IN (value,...))}.
@findex ISNULL()
@item ISNULL(expr)
If @code{expr} is @code{NULL}, @code{ISNULL()} returns @code{1}, otherwise
it returns @code{0}.
it returns @code{0}:
@example
mysql> select ISNULL(1+1);
-> 0
......@@ -14634,7 +14633,7 @@ false!
@findex COALESCE()
@item COALESCE(list)
Returns first non-@code{NULL} element in list.
Returns first non-@code{NULL} element in list:
@example
mysql> select COALESCE(NULL,1);
......@@ -14648,7 +14647,7 @@ mysql> select COALESCE(NULL,NULL,NULL);
Returns @code{0} if @code{N} < @code{N1}, @code{1} if @code{N} < @code{N2}
and so on. All arguments are treated as integers. It is required that
@code{N1} < @code{N2} < @code{N3} < @code{...} < @code{Nn} for this function
to work correctly. This is because a binary search is used (very fast).
to work correctly. This is because a binary search is used (very fast):
@example
mysql> select INTERVAL(23, 1, 15, 17, 30, 44, 200);
......@@ -14663,7 +14662,7 @@ mysql> select INTERVAL(22, 23, 30, 44, 200);
@findex String comparison functions
@findex Functions, string comparison
@node String comparison functions, Casts, Comparison functions, Functions
@subsection String comparison functions
@subsection String Comparison Functions
@cindex Case sensitivity, in string comparisons
@cindex String comparisons, case sensitivity
......@@ -14675,7 +14674,7 @@ comparison is performed in case-sensitive fashion.
@item expr LIKE pat [ESCAPE 'escape-char']
Pattern matching using
SQL simple regular expression comparison. Returns @code{1} (TRUE) or @code{0}
(FALSE). With @code{LIKE} you can use the following two wildcard characters
(FALSE). With @code{LIKE} you can use the following two wild card characters
in the pattern:
@multitable @columnfractions .1 .9
......@@ -14690,7 +14689,7 @@ mysql> select 'David!' LIKE '%D%v%';
-> 1
@end example
To test for literal instances of a wildcard character, precede the character
To test for literal instances of a wild card character, precede the character
with the escape character. If you don't specify the @code{ESCAPE} character,
@samp{\} is assumed:
......@@ -14721,11 +14720,11 @@ mysql> select 10 LIKE '1%';
-> 1
@end example
Note: Because @strong{MySQL} uses the C escape syntax in strings (e.g.,
Note: Because @strong{MySQL} uses the C escape syntax in strings (for example,
@samp{\n}), you must double any @samp{\} that you use in your @code{LIKE}
strings. For example, to search for @samp{\n}, specify it as @samp{\\n}. To
search for @samp{\}, specify it as @samp{\\\\} (the backslashes are stripped
once by the parser, and another time when the pattern match is done, leaving
once by the parser and another time when the pattern match is done, leaving
a single backslash to be matched).
@findex NOT LIKE
......@@ -14743,9 +14742,9 @@ Performs a pattern match of a string expression @code{expr} against a pattern
@xref{Regexp}. Returns @code{1} if @code{expr} matches @code{pat}, otherwise
returns @code{0}. @code{RLIKE} is a synonym for @code{REGEXP}, provided for
@code{mSQL} compatibility. Note: Because @strong{MySQL} uses the C escape
syntax in strings (e.g., @samp{\n}), you must double any @samp{\} that you
use in your @code{REGEXP} strings. As of @strong{MySQL} 3.23.4,
@code{REGEXP} is case insensitive for normal (not binary) strings.
syntax in strings (for example, @samp{\n}), you must double any @samp{\} that
you use in your @code{REGEXP} strings. As of @strong{MySQL} Version 3.23.4,
@code{REGEXP} is case insensitive for normal (not binary) strings:
@example
mysql> select 'Monty!' REGEXP 'm%y%%';
......@@ -14772,7 +14771,7 @@ Same as @code{NOT (expr REGEXP pat)}.
@code{STRCMP()}
returns @code{0} if the strings are the same, @code{-1} if the first
argument is smaller than the second according to the current sort order,
and @code{1} otherwise.
and @code{1} otherwise:
@example
mysql> select STRCMP('text', 'text2');
......@@ -14788,23 +14787,24 @@ mysql> select STRCMP('text', 'text');
@code{MATCH ... AGAINST()} is used for full-text search and returns
relevance - similarity measure between the text in columns
@code{(col1,col2,...)} and the query @code{expr}. Relevance is a
positive floating point number. Zero relevance means no similarity.
positive floating-point number. Zero relevance means no similarity.
For @code{MATCH ... AGAINST()} to work, a @strong{FULLTEXT} index
must be created first. @xref{CREATE TABLE, , @code{CREATE TABLE}}.
@code{MATCH ... AGAINST()} is available in @strong{MySQL} 3.23.23 or later.
For details and usage examples see @xref{MySQL full-text search}.
@code{MATCH ... AGAINST()} is available in @strong{MySQL} Version
3.23.23 or later. For details and usage examples
@pxref{MySQL full-text search}.
@end table
@findex Casts
@node Casts, Control flow functions, String comparison functions, Functions
@subsection Cast operators
@subsection Cast Operators
@table @code
@findex BINARY
@item @code{BINARY}
The @code{BINARY} operator casts the string following it to a binary string.
This is an easy way to force a column comparison to be case sensitive even
if the column isn't defined as @code{BINARY} or @code{BLOB}.
if the column isn't defined as @code{BINARY} or @code{BLOB}:
@example
mysql> select "a" = "A";
-> 1
......@@ -14812,20 +14812,20 @@ mysql> select BINARY "a" = "A";
-> 0
@end example
@code{BINARY} was introduced in @strong{MySQL} 3.23.0
@code{BINARY} was introduced in @strong{MySQL} 3.23.0.
@end table
@findex Control flow functions
@findex Functions, control flow
@node Control flow functions, Mathematical functions, Casts, Functions
@subsection Control flow functions
@subsection Control Flow Functions
@table @code
@findex IFNULL()
@item IFNULL(expr1,expr2)
If @code{expr1} is not @code{NULL}, @code{IFNULL()} returns @code{expr1},
else it returns @code{expr2}. @code{IFNULL()} returns a numeric or string
value, depending on the context in which it is used.
value, depending on the context in which it is used:
@example
mysql> select IFNULL(1,0);
-> 1
......@@ -14840,7 +14840,7 @@ mysql> select IFNULL(1/0,'yes');
@findex NULLIF()
@item NULLIF(expr1,expr2)
If @code{expr1 = expr2} is true, return @code{NULL} else return @code{expr1}.
This is the same as @code{CASE WHEN x = y THEN NULL ELSE x END}
This is the same as @code{CASE WHEN x = y THEN NULL ELSE x END}:
@example
mysql> select NULLIF(1,1);
-> NULL
......@@ -14856,7 +14856,7 @@ are equal.
If @code{expr1} is TRUE (@code{expr1 <> 0} and @code{expr1 <> NULL}) then
@code{IF()} returns @code{expr2}, else it returns @code{expr3}.
@code{IF()} returns a numeric or string value, depending on the context
in which it is used.
in which it is used:
@example
mysql> select IF(1>2,2,3);
......@@ -14869,7 +14869,7 @@ mysql> select IF(strcmp('test','test1'),'no','yes');
@code{expr1} is evaluated as an integer value, which means that if you are
testing floating-point or string values, you should do so using a comparison
operation.
operation:
@example
mysql> select IF(0.1,1,0);
......@@ -14884,10 +14884,10 @@ may not be what you expect. In the second case, the comparison tests the
original floating-point value to see whether it is non-zero. The result
of the comparison is used as an integer.
The default return type of @code{IF()} (which may matter when it stored into
a temporary table) is calculated in @strong{MySQL} 3.23 as follows:
The default return type of @code{IF()} (which may matter when it is stored into
a temporary table) is calculated in @strong{MySQL} Version 3.23 as follows:
@multitable @columnfractions .7 .3
@multitable @columnfractions .55 .45
@item @strong{Expression} @tab @strong{Return value}
@item expr2 or expr3 returns string @tab string
@item expr2 or expr3 returns a floating point value @tab floating point
......@@ -14900,9 +14900,9 @@ a temporary table) is calculated in @strong{MySQL} 3.23 as follows:
The first version returns the @code{result} where
@code{value=compare-value}. The second version returns the result for
the first condition which is true. If there was no matching result
the first condition, which is true. If there was no matching result
value, then the result after @code{ELSE} is returned. If there is no
@code{ELSE} part then @code{NULL} is returned.
@code{ELSE} part then @code{NULL} is returned:
@example
mysql> SELECT CASE 1 WHEN 1 THEN "one" WHEN 2 THEN "two" ELSE "more" END;
......@@ -14917,7 +14917,7 @@ mysql> SELECT CASE BINARY "B" when "a" then 1 when "b" then 2 END;
@findex Mathematical functions
@findex Functions, mathematical
@node Mathematical functions, String functions, Control flow functions, Functions
@subsection Mathematical functions
@subsection Mathematical Functions
All mathematical functions return @code{NULL} in case of an error.
@table @code
......@@ -14925,7 +14925,7 @@ All mathematical functions return @code{NULL} in case of an error.
@findex minus, unary (-)
@findex unary minus (-)
@item -
Unary minus. Changes the sign of the argument.
Unary minus. Changes the sign of the argument:
@example
mysql> select - 2;
-> -2
......@@ -14937,7 +14937,7 @@ may have the value of @code{-2^63}!
@findex ABS()
@item ABS(X)
Returns the absolute value of @code{X}.
Returns the absolute value of @code{X}:
@example
mysql> select ABS(2);
-> 2
......@@ -14949,8 +14949,8 @@ This function is safe to use with @code{BIGINT} values.
@findex SIGN()
@item SIGN(X)
Returns the sign of the argument as @code{-1}, @code{0} or @code{1}, depending
on whether @code{X} is negative, zero, or positive.
Returns the sign of the argument as @code{-1}, @code{0}, or @code{1}, depending
on whether @code{X} is negative, zero, or positive:
@example
mysql> select SIGN(-32);
-> -1
......@@ -14966,7 +14966,7 @@ mysql> select SIGN(234);
@item MOD(N,M)
@itemx %
Modulo (like the @code{%} operator in C).
Returns the remainder of @code{N} divided by @code{M}.
Returns the remainder of @code{N} divided by @code{M}:
@example
mysql> select MOD(234, 10);
-> 4
......@@ -14980,7 +14980,7 @@ This function is safe to use with @code{BIGINT} values.
@findex FLOOR()
@item FLOOR(X)
Returns the largest integer value not greater than @code{X}.
Returns the largest integer value not greater than @code{X}:
@example
mysql> select FLOOR(1.23);
-> 1
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7