MySQL Stored Procedure | How to write it? - mysql

Question

This time I have a MySQL question, I'm trying to create a stored procedure which will execute a prepared statement, the goal is to get a ranged list from a table("order_info"), the list is divided by "pages", each page is determined by a record count and should be ordered using a particular field sorted either 'ASC' or 'DESC', each record represents an "order" the catch here is that the procedure returns the orders of a particular group, the the order is associated to a user which belongs to a group. Here's what I've done so far:
CREATE DEFINER=`root`#`%` PROCEDURE `getGroupOrders`(IN grp INT,
IN page INT,
IN count INT,
IN ord TINYINT,
IN srt VARCHAR(4)
)
BEGIN
PREPARE prepGroupOrders FROM
"SELECT oi.* FROM `dbre`.`order_info` oi
INNER JOIN `dbre`.`users` usr
ON oi.`username` = usr.`username` AND usr.`id_group` = ?
ORDER BY ? ? LIMIT ?, ?";
SET #g := grp;
SET #cnt := count;
SET #start := #page*count ;
SET #orderBy := ord;
SET #sortBy := srt;
EXECUTE prepGroupOrders USING #g,#orderBy,#sortBy,#start,#cnt;
END
I get a syntax error when executing this, even though the editor does not higlight any errors and lets me save the procedure,I think that one of the follwing may be happening:
I am incorrectly usng the `ASC` or `DESC` since it is a SQL reserved word.
I read somewhere that Prepared statement are for only ONE SQL query, and since I have nested queries it can't be done.
I've tested this standard query:
SELECT oi.* FROM `dbre`.`order_info` oi
INNER JOIN `dbre`.`users` usr
ON oi.`username` = usr.`username` AND usr.`id_group` = 1
ORDER BY `status` DESC LIMIT 5, 10;
And it gives me the results I want. SO how would I design the procedure?
Any help is truly appreciated.

Answer 1

This may not necessarily solve your issue but, you can probably clean that query up a bit, eliminate the subquery and get something that should perform a little better.
SELECT oi.*
FROM `dbre`.`order_info` oi
INNER JOIN `dbre`.`users` u
ON oi.username = u.username
AND u.id_group = 1
ORDER BY `status` DESC
LIMIT 5, 10;