Fixed that EXPLAIN EXTENDED erroneously returned
"SQL%%ROWCOUNT" instead of "SQL%ROWCOUNT"

Adding Oracle-specific tests for stored functions as EXECUTE..USING parameters.

Adding Oracle specific tests

Adding Oracle specific tests

Adding the Oracle style DECODE function:

  DECODE(operand, search, result [, search, result ...] [, default_result])

MDEV-10596 Allow VARCHAR and VARCHAR2 without length as a data type of routine parameters and in RETURN clause

The crash happened because of a wrong reset_lex() .. restore_lex() sequence.
The Item in WHERE clause and the corresponding sp_instr_jump_if_not() were
erroneously created using different LEX.

This is a fix for "MDEV-10580 sql_mode=ORACLE: FOR loop statement"
The tokenizer now treats digits followed by two dots (e.g. '1..')
as an integer number '1' followed by DOT_DOT_SYM.
Previously this sequence was treated as a double number '1.' followed by '.'.

Fixed a crash when trying to use a FOR loop as a compound statement
outside of an SP. A bug in 051e415d8a251bd70e9b73619dbcc40f3c65371d.

Adding functions NVL() and NVL2().

as this type of SHOW is only available in debug builds.
A bug in b7af3e704dd7800638ef677e9d921ad3e467a9a6.
All SHOW FUNCTION CODE queries should be in compat/oracle.sp-code.

Part 19: CONTINUE statement

Fixed that the ITERATE statement inside a FOR LOOP statement did not
increment the index variable before jumping to the beginning
of the loop, which caused the loop to repeat endlessly.

Adding labeled FOR LOOP

Adding non-labeled FOR LOOP statement.

from "const Lex_field_type_st &" to "const Column_definition &".

Adding methods:
- LEX::sp_while_loop_expression()
- LEX::sp_while_loop_finalize()

to reuse code between sql_yacc.yy and sql_yacc_ora.yy.
FOR loop will also reuse these methods.

Part 18: WHILE syntax

Part 17: RETURN in stored procedures

Part 16: CURSOR declaration

Part 15: ELSIF vs ELSEIF

Also, moving tests for Oracle keywords in sql_mode=DEFAULT
from "parser.test" to a better place "keywords.test".

Part 5: EXIT statement

Adding optional WHEN clause:

EXIT [label] [WHEN expr]

Part 5: EXIT statement

Adding unconditional EXIT statement:

  EXIT [ label ]

Conditional EXIT statements with WHERE clause
will be added in a separate patch.

Moving similar code from sql_yacc.yy and sql_yacc_ora.yy to methods:
  LEX::maybe_start_compound_statement()
  LEX::sp_push_loop_label()
  LEX::sp_push_loop_empty_label()
  LEX::sp_pop_loop_label()
  LEX::sp_pop_loop_empty_label()

The EXIT statement will also reuse this code.

Moving the code from *.yy to methods:
LEX::sp_change_context()
LEX::sp_leave_statement()
LEX::sp_iterate_statement()
to reuse the same code between LEAVE and ITERATE statements.
EXIT statement will also reuse the same code.

Part 9: EXCEPTION handlers

EXCEPTION is now supported in inner blocks.

When processing an SP body:

CREATE PROCEDURE p1 (parameters)
AS [ declarations ]
BEGIN statements
[ EXCEPTION exceptions ]
END;

the parser generates two "jump" instructions:
- from the end of "declarations" to the beginning of EXCEPTION
- from the end of EXCEPTION to "statements"

These jumps are useless if EXCEPTION does not exist.
This patch makes sure that these two "jump" instructions are
generated only if EXCEPTION really exists.

- Part 9: EXCEPTION handlers

  The top-most stored routine blocks now support EXCEPTION clause
  in its correct place:
  AS [ declarations ]
  BEGIN statements
  [ EXCEPTION exceptions ]
  END

  Inner block will be done in a separate commit.

- Part 14: IN OUT instead of INOUT (in SP parameter declarations)

Part 13: RETURN vs RETURNS in function definition:

  CREATE FUNCTION f1(a INT) RETURN INT ...

Part 12:  No parentheses if no arguments:

  CREATE FUNCTION f1 RETURN INT ...

Part 12: No parentheses if no arguments
Now "CREATE PROCEDURE p1 AS" is supported with no parentheses after the name.
Note, "CREATE FUNCTION f1 AS" is not supported yet, due to grammar conflict
with UDFs. Functions will be done in a separate patch.

Part 11: NULL as a statement

Part 10: Default variable value: x INT := 10;

Part 9: EXCEPTION handlers

- Adding exception handler syntax:
  WHEN exception_name THEN statement
- Adding EXCEPTION section intoi the top BEGIN..END SP block.
  Note, currently EXCEPTION goes in the beginning of the top BEGIN..END
  SP block.

TODO:
- add EXCEPTION section into inner blocks
- move EXCEPTION to the end of the block