Question

I’ve got a stored procedure in my MySQL database, and need to figure out how to limit the return to create some pagination.

Some pseudocode:

CREATE PROCEDURE `my_procedure`(IN member_id INT, IN start INT, IN end INT)
BEGIN
SELECT * FROM member_activity WHERE `member_id` = member_id
<if start is not null>
LIMIT start, end
<endif>
END;

If I pass a null value, how do I simply unlimit the query?

Passing my_procedure(1,null,null) returns an error.

I know I can just wrap the entire query in an IF statement, but I’d rather not, because there’s several other variables that would be annoying to keep in sync. Is it possible to accomplish this without writing the entire query twice?

Thanks

Answer 1

As mentioned in the manual:

To retrieve all rows from a certain offset up to the end of the result set, you can use some large number for the second parameter. This statement retrieves all rows from the 96th row to the last:

SELECT * FROM tbl LIMIT 95,18446744073709551615;

Since, as you point out, one cannot use the IFNULL() function within the LIMIT clause, prior to your SELECT command you could do:

SET `start` := IFNULL(`start`, 0);
SET `end`   := IFNULL(`end`  , 18446744073709551615);