add help command on server side

client/mysql.cc

@@ -205,8 +205,8 @@ typedef struct {
 } COMMANDS;
 
 static COMMANDS commands[] = {
-  { "help",   'h', com_help,   0, "Display this help." },
-  { "?",      '?', com_help,   0, "Synonym for `help'." },
+  { "help",   'h', com_help,   1, "Display this help." },
+  { "?",      '?', com_help,   1, "Synonym for `help'." },
   { "clear",  'c', com_clear,  0, "Clear command."},
   { "connect",'r', com_connect,1,
     "Reconnect to the server. Optional arguments are db and host." },
@@ -382,8 +382,9 @@ int main(int argc,char *argv[])
     }
   }
 #endif
-  sprintf(buff, 
-	  "Type 'help;' or '\\h' for help. Type '\\c' to clear the buffer.\n");
+  sprintf(buff, "%s%s",
+	  "Type 'help;' or '\\h' for help. Type '\\c' to clear the buffer.\n",
+	  "Type 'help [[%]function name[%]]' to get help on usage of function.\n");
   put_info(buff,INFO_INFO);
   status.exit_status=read_lines(1);		// read lines and execute them
   if (opt_outfile)
@@ -1322,19 +1323,141 @@ static int reconnect(void)
  The different commands
 ***************************************************************************/
 
+int mysql_real_query_for_lazy(const char *buf, int length)
+{
+  for (uint retry=0;; retry++)
+  {
+    if (!mysql_real_query(&mysql,buf,length))
+      return 0;    
+    uint error=put_info(mysql_error(&mysql),INFO_ERROR, mysql_errno(&mysql));
+    if (mysql_errno(&mysql) != CR_SERVER_GONE_ERROR || retry > 1 
+	|| status.batch)
+      return error;
+    if (reconnect())
+      return error;
+  }
+}
+
+int mysql_store_result_for_lazy(MYSQL_RES **result)
+{
+  if ((*result=mysql_store_result(&mysql)))
+    return 0;
+
+  if (mysql_error(&mysql)[0])
+    return put_info(mysql_error(&mysql),INFO_ERROR,mysql_errno(&mysql));
+
+  return 0;
+}
+
+static int com_server_help(String *buffer __attribute__((unused)),
+	  char *line __attribute__((unused)), char *help_arg)
+{
+  MYSQL_ROW cur;
+  const char *server_cmd= buffer->ptr();
+  char cmd_buf[100];
+
+  if (help_arg[0]!='\'')
+  {
+    (void*)sprintf(cmd_buf,"help \'%s\';",help_arg);
+    server_cmd= cmd_buf;
+  }
+
+  char buff[16], time_buf[32];
+  MYSQL_RES *result;
+  ulong timer;
+  uint error= 0;
+
+  if (!status.batch)
+  {
+    old_buffer= *buffer;
+    old_buffer.copy();
+  }
+
+  if (!connected && reconnect())
+    return 1;
+
+  timer= start_timer();
+
+  error= mysql_real_query_for_lazy(server_cmd,strlen(server_cmd));
+  if (error)
+    return error;
+
+  error= mysql_store_result_for_lazy(&result);
+  if (error)
+    return error;
+
+  if (result)
+  {
+    int num_rows= mysql_num_rows(result);
+    if (num_rows==1)
+    {
+      if (!(cur= mysql_fetch_row(result)))
+	return -1;
+
+      init_pager();
+      if (cur[1][0]=='Y')
+      {
+	tee_fprintf(PAGER, "\nHelp topic \'%s\'\n", cur[0]);
+	tee_fprintf(PAGER, "%s\n", cur[2]);
+	tee_fprintf(PAGER, "For help on specific function please type 'help <function>' where function is one of next :\n%s\n", cur[3]);
+      }
+      else
+      {
+	tee_fprintf(PAGER, "\nName : \'%s\'\n\n", cur[0]);
+	tee_fprintf(PAGER, "Description : \n%s\n\n", cur[2]);
+	tee_fprintf(PAGER, "Examples : \n%s\n", cur[3]);
+      }
+      end_pager();
+    }
+    else if (num_rows>1)
+    {
+      put_info("\nMany help items for your request exist", INFO_INFO);
+      put_info("For more specific request please type 'help <item>' where item is one of next :", INFO_INFO);
+
+      init_pager();
+      char last_char= '_';
+      while ((cur= mysql_fetch_row(result))){
+	if (cur[1][0]!=last_char){
+	  put_info("-------------------------------------------", INFO_INFO);
+	  put_info(cur[1][0]=='Y' ? 
+		   "categories:" : "functions:", INFO_INFO);
+	  put_info("-------------------------------------------", INFO_INFO);
+	}
+	last_char= cur[1][0];
+	tee_fprintf(PAGER, "%s\n", cur[0]);
+      }
+      tee_fprintf(PAGER, "\n");
+      end_pager();
+    }
+    else
+    {
+      put_info("\nNothing found\n", INFO_INFO);
+    }
+  }
+
+  mysql_free_result(result);
+  return error;
+}
+
 static int
 com_help (String *buffer __attribute__((unused)),
 	  char *line __attribute__((unused)))
 {
   reg1 int i;
+  char * help_arg= strchr(line,' ');
 
+  if (help_arg)
+  {
+    return com_server_help(buffer,line,help_arg+1);
+  }
+  else
+  {
     put_info("\nFor the complete MySQL Manual online visit:\n   http://www.mysql.com/documentation\n", INFO_INFO);
     put_info("For info on technical support from MySQL developers visit:\n   http://www.mysql.com/support\n", INFO_INFO);
     put_info("For info on MySQL books, utilities, consultants, etc. visit:\n   http://www.mysql.com/portal\n", INFO_INFO);
     put_info("List of all MySQL commands:", INFO_INFO);
     if (!named_cmds)
-    put_info("   (Commands must appear first on line and end with ';')\n",
-	     INFO_INFO);
+      put_info("Note that all text commands must be first on line and end with ';'",INFO_INFO);
     for (i = 0; commands[i].name; i++)
     {
       if (commands[i].func)
@@ -1347,6 +1470,7 @@ com_help (String *buffer __attribute__((unused)),
 		mysql_thread_id(&mysql));
     else
       tee_fprintf(stdout, "Not connected!  Reconnect with 'connect'!\n\n");
+  }
   return 0;
 }
 
@@ -1411,23 +1535,14 @@ com_go(String *buffer,char *line __attribute__((unused)))
   }
 
   timer=start_timer();
-  for (uint retry=0;; retry++)
-  {
-    if (!mysql_real_query(&mysql,buffer->ptr(),buffer->length()))
-      break;
-    error=put_info(mysql_error(&mysql),INFO_ERROR, mysql_errno(&mysql));
-    if (mysql_errno(&mysql) != CR_SERVER_GONE_ERROR || retry > 1 
-	|| status.batch)
-    {
-      buffer->length(0);			// Remove query on error
-      return error;
-    }
-    if (reconnect())
+
+  error= mysql_real_query_for_lazy(buffer->ptr(),buffer->length());
+  if (error)
   {
     buffer->length(0); // Remove query on error
     return error;
   }
-  }
+
   error=0;
   buffer->length(0);
 
@@ -1440,13 +1555,9 @@ com_go(String *buffer,char *line __attribute__((unused)))
   }
   else
   {
-    if (!(result=mysql_store_result(&mysql)))
-    {
-      if (mysql_error(&mysql)[0])
-      {
-	return put_info(mysql_error(&mysql),INFO_ERROR,mysql_errno(&mysql));
-      }
-    }
+    error= mysql_store_result_for_lazy(&result);
+    if (error)
+      return error;
   }
 
   if (verbose >= 3 || !opt_silent)
@@ -2772,3 +2883,5 @@ void sql_element_free(void *ptr)
   my_free((gptr) ptr,MYF(0));
 }
 #endif /* EMBEDDED_LIBRARY */
+
+

include/mysqld_error.h

@@ -258,4 +258,5 @@
 #define ER_SUBSELECT_NO_1_COL 1239
 #define ER_SUBSELECT_NO_1_ROW 1240
 #define ER_UNKNOWN_STMT_HANDLER 1241
+#define ER_CORRUPT_HELP_DB 1242
 #define ER_ERROR_MESSAGES 242

scripts/Makefile.am

@@ -52,11 +52,13 @@ EXTRA_SCRIPTS =		make_binary_distribution.sh \
 			mysql_explain_log.sh \
 			mysqld_multi.sh \
 			mysql_tableinfo.sh \
-			mysqld_safe.sh
+			mysqld_safe.sh \
+			fill_func_tables.sh
 
 EXTRA_DIST =		$(EXTRA_SCRIPTS) \
 			mysqlaccess.conf \
-			mysqlbug
+			mysqlbug \
+                        fill_func_tables.sql
 
 pkgdata_DATA =		make_binary_distribution
 
@@ -76,7 +78,8 @@ CLEANFILES =		@server_scripts@ \
 			mysql_find_rows \
 			mysqlhotcopy \
 			mysqldumpslow \
-			mysqld_multi
+			mysqld_multi \
+                        fill_func_tables.sql
 
 SUPERCLEANFILES =	mysqlbug
 
@@ -127,3 +130,8 @@ SUFFIXES = .sh
 
 # Don't update the files from bitkeeper
 %::SCCS/s.%
+
+all: fill_func_tables.sql
+
+fill_func_tables.sql: fill_func_tables ../Docs/manual.texi
+	./fill_func_tables < ../Docs/manual.texi > fill_func_tables.sql
\ No newline at end of file

scripts/fill_func_tables.sh

+#!@PERL@
+# fill_func_tables - parse ../Docs/manual.texi 
+
+# Original version by vva 
+
+my $cat_name= "";
+my $func_name= "";
+my $text= "";
+my $example= "";
+
+local $mode= "";
+
+sub prepare_name
+{
+  my ($a)= @_;
+
+  $a =~ s/(\@itemize \@bullet)/  /g;
+  $a =~ s/(\@end itemize)/  /g;
+  $a =~ s/(\@end multitable)/  /g;
+  $a =~ s/(\@end table)/  /g;
+  $a =~ s/(\@cindex(.*?)\n)/  /g;
+  $a =~ s/(\@multitable \@columnfractions(.*?)\n)/  /g;
+  $a =~ s/(\@node(.*?)\n)/  /g;
+  $a =~ s/(\@tab)/\t/g;
+  $a =~ s/\@item/  /g;
+  $a =~ s/\@code\{((.|\n)+?)\}/$1/go;
+  $a =~ s/\@strong\{(.+?)\}/$1/go;
+  $a =~ s/\@samp\{(.+?)\}/$1/go;
+  $a =~ s/\@emph\{((.|\n)+?)\}/\/$1\//go;
+  $a =~ s/\@xref\{((.|\n)+?)\}/See also : [$1]/go;
+  $a =~ s/\@ref\{((.|\n)+?)\}/[$1]/go;
+  $a =~ s/\'/\'\'/g;
+  $a =~ s/\\/\\\\/g;
+  $a =~ s/\`/\`\`/g;
+
+  $a =~ s/\@table \@code/  /g;
+
+  $a =~ s/\(\)//g;
+
+  $a =~ s/((\w|\s)+)\(([\+-=><\/%*!<>\s]+)\)/$3/gxs; #$a =~ s/((\w|\s)+)\(([\+-=><\/%*!<>\s]+)\)/$3 $1/gxs;
+  $a =~ s/([\+-=><\/%*!<>\s]+)\(((\w|\s)+)\)/$1/gxs;#$a =~ s/([\+-=><\/%*!<>\s]+)\(((\w|\s)+)\)/$1 $2/gxs;
+  $a =~ s/((\w|\s)+)\((.+)\)/$1/gxs;
+
+  return $a;
+}
+
+sub prepare_text
+{
+  my ($a)= @_;
+
+  $a =~ s/(\@itemize \@bullet)/  /g;
+  $a =~ s/(\@end itemize)/  /g;
+  $a =~ s/(\@end multitable)/  /g;
+  $a =~ s/(\@end table)/  /g;
+  $a =~ s/(\@cindex(.*?)\n)/  /g;
+  $a =~ s/(\@multitable \@columnfractions(.*?)\n)/  /g;
+  $a =~ s/(\@node(.*?)\n)/  /g;
+  $a =~ s/(\@tab)/\t/g;
+  $a =~ s/\@itemx/  /g;
+  $a =~ s/\@item/  /g;
+  $a =~ s/\@code\{((.|\n)+?)\}/$1/go;
+  $a =~ s/\@strong\{(.+?)\}/$1/go;
+  $a =~ s/\@samp\{(.+?)\}/$1/go;
+  $a =~ s/\@emph\{((.|\n)+?)\}/\/$1\//go;
+  $a =~ s/\@xref\{((.|\n)+?)\}/See also : [$1]/go;
+  $a =~ s/\@ref\{((.|\n)+?)\}/[$1]/go;
+  $a =~ s/\'/\'\'/g;
+  $a =~ s/\\/\\\\/g;
+  $a =~ s/\`/\`\`/g;
+  $a =~ s/(\n*?)$//g;
+  $a =~ s/\n/\\n/g;
+
+  $a =~ s/\@table \@code/  /g;
+
+  return $a;
+}
+
+sub prepare_example
+{
+  my ($a)= @_;
+
+  $a =~ s/\'/\'\'/g;
+  $a =~ s/\\/\\\\/g;
+  $a =~ s/\`/\`\`/g;
+  $a =~ s/(\n*?)$//g;
+  $a =~ s/\n/\\n/g;
+
+  return $a;
+}
+
+sub flush_all
+{
+  my ($mode) = @_;
+
+  if ($mode eq ""){return;}
+
+  $func_name= prepare_name($func_name);
+  $text= prepare_text($text);
+  $example= prepare_example($example);
+
+  if ($func_name ne "" && $text ne "" && !($func_name =~ /[abcdefghikjlmnopqrstuvwxyz]/)){
+    print "INSERT INTO function (name,description,example) VALUES (";
+    print "'$func_name',";
+    print "'$text',";
+    print "'$example'";
+    print ");\n";
+    print "INSERT INTO function_category (cat_id,func_id) VALUES (\@cur_category,LAST_INSERT_ID());\n";
+  }
+
+  $func_name= "";
+  $text= "";
+  $example= "";
+  $mode= "";
+}
+
+sub new_category
+{
+  my ($category)= @_;
+
+  $category= prepare_text($category);
+
+  print "INSERT INTO function_category_name (name) VALUES (\'$category\');\n";
+  print "SELECT \@cur_category:=LAST_INSERT_ID();\n";
+}
+
+print "INSERT INTO db (Host,DB,User,Select_priv) VALUES ('%','mysql_help','','Y');\n";
+print "CREATE DATABASE mysql_help;\n";
+
+print "USE mysql_help;\n";
+
+print "DROP TABLE IF EXISTS function;\n";
+print "CREATE TABLE function (";
+print "  func_id       int unsigned not null auto_increment,";
+print "  name          varchar(64) not null,";
+print "  url           varchar(128) not null,";
+print "  description   text not null,";
+print "  example       text not null,";
+print "  min_args      tinyint not null,";
+print "  max_args      tinyint,";
+print "  date_created  datetime not null,";
+print "  last_modified timestamp not null,";
+print "  primary key   (func_id)";
+print ") type=myisam;\n\n";
+
+print "DROP TABLE IF EXISTS function_category_name;\n";
+print "CREATE TABLE function_category_name (";
+print "  cat_id        smallint unsigned not null auto_increment,";
+print "  name          varchar(64) not null,";
+print "  url           varchar(128) not null,";
+print "  date_created  datetime not null,";
+print "  last_modified timestamp not null,";
+print "  primary key   (cat_id)";
+print ") type=myisam;\n\n";
+
+print "DROP TABLE IF EXISTS function_category;\n";
+print "CREATE TABLE function_category (";
+print "  cat_id        smallint unsigned not null references function_category_name,";
+print "  func_id       int unsigned not null references function,";
+print "  primary key   (cat_id, func_id)";
+print ") type=myisam;\n\n";
+
+print "DELETE FROM function_category_name;\n";
+print "DELETE FROM function_category;\n";
+print "DELETE FROM function;\n";
+print "SELECT \@cur_category:=null;\n\n";
+
+my $in_section_6_3= 0;
+
+for(<>)
+{
+  if ($_=~/\@section Functions for Use in \@code{SELECT} and \@code{WHERE} Clauses/ &&
+      !$in_section_6_3){
+    $in_section_6_3= 1;
+    next;
+  }
+
+  if ($_=~/\@section/ && $in_section_6_3){
+    $in_section_6_3= 0;
+    next;
+  }
+
+  if (!$in_section_6_3) { next; }
+
+  my $c_name= "";
+
+  ($c_name)=m|\@c for_mysql_help,(.+?)$|;
+  if (!($c_name eq "") && ! ($c_name =~ m/$cat_name/i)){
+    ($cat_name)= $c_name;
+    new_category($cat_name);
+    next;
+  }
+
+  ($c_name)=m|\@subsubsection (.+?)$|;
+  if (!($c_name eq "") && ! ($c_name =~ m/$cat_name/i)){
+    ($cat_name)= $c_name;
+    new_category($cat_name);
+    next;
+  }
+
+  ($c_name)=m|\@subsection (.+?)$|;
+  if (!($c_name eq "") && ! ($c_name =~ m/$cat_name/i)){
+    ($cat_name)= $c_name;
+    new_category($cat_name);
+    next;
+  }
+
+  ($f_name)=m|\@findex (.+?)$|;
+  if (!($f_name eq "")){
+    flush_all($mode);
+    ($func_name)= ($f_name);
+    $mode= "text";
+    next;
+  }
+
+  if ($_=~/\@example/ && ($mode eq "text")){
+    $mode= "example";
+    next;
+  }
+
+  if ($_=~/\@end example/ && ($mode eq "example")){
+    flush_all($mode);
+    next;
+  }
+
+  if ($mode eq "text")    { $text    .= $_; }
+  if ($mode eq "example") { $example .= $_; }
+}
+
+
+print "DELETE function_category_name ";
+print "FROM function_category_name ";
+print "LEFT JOIN function_category ON function_category.cat_id=function_category_name.cat_id ";
+print "WHERE function_category.cat_id is null;"
+

scripts/mysql_install_db.sh

@@ -307,8 +307,8 @@ then
 fi
 
 echo "Installing all prepared tables"
-if eval "$execdir/mysqld $defaults --bootstrap --skip-grant-tables \
-         --basedir=$basedir --datadir=$ldata --skip-innodb --skip-bdb $args" << END_OF_DATA
+if (
+    cat << END_OF_DATA
 use mysql;
 $c_d
 $i_d
@@ -325,6 +325,9 @@ $i_f
 $c_t
 $c_c
 END_OF_DATA
+    cat fill_func_tables.sql
+) | eval "$execdir/mysqld $defaults --bootstrap --skip-grant-tables \
+         --basedir=$basedir --datadir=$ldata --skip-innodb --skip-bdb $args" 
 then
   echo ""
   if test "$IN_RPM" -eq 0

sql/Makefile.am

@@ -84,7 +84,7 @@ mysqld_SOURCES =	sql_lex.cc sql_handler.cc \
 			slave.cc sql_repl.cc sql_union.cc sql_derived.cc \
 			mini_client.cc mini_client_errors.c \
 			stacktrace.c repl_failsafe.h repl_failsafe.cc sql_olap.cc\
-			gstream.cc spatial.cc
+			gstream.cc spatial.cc sql_help.cc
 gen_lex_hash_SOURCES =	gen_lex_hash.cc
 gen_lex_hash_LDADD =	$(LDADD) $(CXXLDFLAGS)
 

sql/lex.h

@@ -172,6 +172,7 @@ static SYMBOL symbols[] = {
   { "HANDLER",		SYM(HANDLER_SYM),0,0},
   { "HASH",		SYM(HASH_SYM),0,0},
   { "HEAP",		SYM(HEAP_SYM),0,0},
+  { "HELP",		SYM(HELP),0,0},
   { "HIGH_PRIORITY",	SYM(HIGH_PRIORITY),0,0},
   { "HOUR",		SYM(HOUR_SYM),0,0},
   { "HOUR_MINUTE",	SYM(HOUR_MINUTE_SYM),0,0},

sql/mysql_priv.h

@@ -505,6 +505,7 @@ int mysqld_show_charsets(THD *thd,const char *wild);
 int mysqld_show_table_types(THD *thd);
 int mysqld_show_privileges(THD *thd);
 int mysqld_show_column_types(THD *thd);
+int mysqld_help (THD *thd, const char *text);
 
 /* sql_prepare.cc */
 int compare_prep_stmt(PREP_STMT *a, PREP_STMT *b, void *not_used);

sql/share/czech/errmsg.txt

@@ -252,3 +252,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/danish/errmsg.txt

@@ -246,3 +246,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/dutch/errmsg.txt

@@ -254,3 +254,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/english/errmsg.txt

@@ -243,3 +243,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/estonian/errmsg.txt

@@ -248,3 +248,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/french/errmsg.txt

@@ -243,3 +243,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/german/errmsg.txt

@@ -246,3 +246,4 @@
 "Subselect return more than 1 field",
 "Subselect return more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/greek/errmsg.txt

@@ -243,3 +243,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/hungarian/errmsg.txt

@@ -245,3 +245,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/italian/errmsg.txt

@@ -243,3 +243,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/japanese/errmsg.txt

@@ -245,3 +245,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/korean/errmsg.txt

@@ -243,3 +243,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/norwegian-ny/errmsg.txt

@@ -245,3 +245,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/norwegian/errmsg.txt

@@ -245,3 +245,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/polish/errmsg.txt

@@ -247,3 +247,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/portuguese/errmsg.txt

@@ -243,3 +243,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/romanian/errmsg.txt

@@ -247,3 +247,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/russian/errmsg.txt

@@ -246,3 +246,4 @@
 "    ",
 "    ",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/serbian/errmsg.txt

@@ -239,3 +239,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/slovak/errmsg.txt

@@ -251,3 +251,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/spanish/errmsg.txt

@@ -244,3 +244,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/swedish/errmsg.txt

@@ -243,3 +243,4 @@
 "Subselect returns more than 1 field",
 "Subselect returns more than 1 record",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/share/ukrainian/errmsg.txt

@@ -248,3 +248,4 @@
 "i  i i 1 ",
 "i  i i 1 ",
 "Unknown prepared statement handler (%ld) given to %s",
+"Corrupt or doesn\'t exist help database",

sql/sql_lex.h

@@ -66,7 +66,7 @@ enum enum_sql_command {
   SQLCOM_SHOW_BINLOG_EVENTS, SQLCOM_SHOW_NEW_MASTER, SQLCOM_DO,
   SQLCOM_SHOW_WARNS, SQLCOM_EMPTY_QUERY, SQLCOM_SHOW_ERRORS,
   SQLCOM_SHOW_COLUMN_TYPES, SQLCOM_SHOW_TABLE_TYPES, SQLCOM_SHOW_PRIVILEGES,
-  SQLCOM_END
+  SQLCOM_END, SQLCOM_HELP,
 };
 
 enum lex_states
@@ -383,6 +383,7 @@ typedef struct st_lex
   bool derived_tables, describe;
   uint slave_thd_opt;
   CHARSET_INFO *charset;
+  char *help_arg;
 } LEX;
 
 

sql/sql_parse.cc

@@ -1486,6 +1486,10 @@ mysql_execute_command(THD *thd)
     send_ok(thd);
     break;
 
+  case SQLCOM_HELP:
+    res= mysqld_help(thd,lex->help_arg);
+    break;
+
   case SQLCOM_PURGE:
   {
     if (check_global_access(thd, SUPER_ACL))

sql/sql_yacc.yy

@@ -505,6 +505,8 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token  SUBJECT_SYM
 %token  CIPHER_SYM
 
+%token  HELP
+
 %left   SET_VAR
 %left	OR_OR_CONCAT OR
 %left	AND
@@ -637,7 +639,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 	handler_rkey_function handler_read_or_scan
 	single_multi table_wild_list table_wild_one opt_wild union union_list
 	precision union_option opt_on_delete_item subselect_start opt_and
-	subselect_end select_var_list select_var_list_init
+	subselect_end select_var_list select_var_list_init help
 END_OF_INPUT
 
 %type <NONE>
@@ -699,7 +701,18 @@ verb_clause:
 	| handler
 	| unlock
 	| update
-	| use;
+	| use
+	| help;
+	
+/* help */
+
+help: 
+       HELP TEXT_STRING
+       {
+       LEX *lex= Lex;
+       lex->sql_command= SQLCOM_HELP;
+       lex->help_arg= $2.str;
+       }
 
 /* change master */