[Firebird-docs] Minor FIRST/LIMIT syntax change

[John B. <bel...@cs...>]

Hi,
	Mark O. found a bug in the syntax for FIRST/SKIP that has resulting 
in a small syntax change.  The bug is as follows:

in the query "SELECT LIMIT 5 * FROM MESSAGES" the parser was treating 
'5 * FROM' as a multiplication equation.  It would generate an error 
because FROM is not valid in the equation.  The new syntax is slightly 
changed:

SELECT [LIMIT X | LIMIT ? | LIMIT ( expression )] [SKIP X | SKIP ? | 
SKIP ( expression )] ....

The difference is now X can only be a long integer constant, not a full 
expression (ie, equation).  If you want to use an equation or anything 
other than a bind variable or integer constant you *must* include the 
parens.  That is the change.

'SELECT LIMIT 5 * FROM MESSAGES' now works (and the syntax for that 
query is unchanged).  But the syntax for 'SELECT LIMIT 5*4 SKIP 1+5*3 * 
FROM MESSAGES' (notice how the bug is easy to spot here) is now 'SELECT 
LIMIT (5*4) SKIP (1+5*3) * FROM MESSAGES'


>> SELECT [FIRST X] [SKIP X] [DISTINCT | ALL] ....
>>
>> all indicies are 1 based.  The new SQL keywords introduced are FIRST 
>> and SKIP.
>
> Both FIRST and SKIP work on their own.  Combining both FIRST and SKIP 
> gives you limit functionality.

-John