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Mysql - Assign variable on EXISTS clause.

Posted on 2009-07-04
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Last Modified: 2012-05-07
How to assign a value inside a EXISTS clause in a Mysql function.

This code bellow (UID) is returning NULL.
Please help.
CREATE FUNCTION LOG_STATUS (LID int) RETURNS char(9)
BEGIN
    DECLARE UID char(9);
    IF EXISTS(SELECT USR_ID INTO UID FROM `logs` WHERE ID=LID AND LOGOUT='0000-00-00 00:00:00') THEN
        RETURN UID;
    ELSE
       RETURN 'NO';
    END IF;
END

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Question by:ricarmpo
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2 Comments
 
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Expert Comment

by:mrjoltcola
ID: 24777821
What is UID for that row? It could be actually NULL.
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Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 250 total points
ID: 24777825
you cannot put INTO inside of EXISTS.

I would consider this method:
CREATE FUNCTION LOG_STATUS (LID int) RETURNS char(9)
BEGIN
    DECLARE UID char(9);
    SELECT USR_ID INTO UID FROM `logs` WHERE ID=LID AND LOGOUT='0000-00-00 00:00:00'; 
    RETURN COALESCE(UID, 'NO');
END

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