Stored procedures

[poizn]

Hi all

 

I have 2 question's.

Recently I have started trying to impliment stored procedures in our application, but am having a little trouble learning everything. My first question is can a stored procedure return more than one record. In other words, if I had a stored procedure, that fetched all the records from a table, could I get all the records returned from the stored procedure?

 

DELIMITER $$

DROP PROCEDURE IF EXISTS `test`.`p2` $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `p2`(OUT user_ids INTEGER(10))
BEGIN
  SELECT DISTINCT user_id INTO user_ids
  FROM users;
END $$

DELIMITER ;

 

Lets assume this is my simple stored procedure, I call it like so

CALL p2(@var);

 

And get the following error message

"Error 1172: Result consisted of more than one row"

 

Can anyone help?

 

My second question isn't really a stored procedures question, but more of a query related question.

Lets assume I have a users table, with a user_id column.

I then have a user_group table, with a user_id, and group_id column.

Given that a group can be any size (ie there can be multiple records in the user_group table for a given group) how can I check if a group exists, given the user_id's? And if the group does exist, return the group_id?

 

Can any one help?

 

Thanks in advance