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mysqlselecton-duplicate-key

MySQL INSERT on duplicate key UPDATE with SELECT


I have a query like the following

INSERT INTO connections (`c_id`,`in`,`out`,`ip`,`userID`) 
VALUES ( 
    ( 
        SELECT c_id 
        FROM connections 
        WHERE (a bunch of conditions) 
        ORDER BY c_id DESC LIMIT 1 

    ),
    '1373799802',
    0,
    INET_ATON('127.0.0.1'),
    4

) 
ON DUPLICATE KEY UPDATE `out` = 1

Which throws the following error

1093 - You can't specify target table 'connections' for update in FROM clause

Obviously I can't have a SELECT clause within the insert into on duplicate update syntax, but I'd really rather do that instead of have 2 queries running. Can anyone tell me how I can do this?


Solution

  • Try like this instead:

    INSERT INTO connections (`c_id`,`in`,`out`,`ip`,`userID`) 
    VALUES ( 
        ( 
    SELECT p.c_id 
            FROM (select * from connections) p 
            WHERE (a bunch of conditions) 
            ORDER BY p.c_id DESC LIMIT 1 
    
        ),
        '1373799802',
        0,
        INET_ATON('127.0.0.1'),
        4
    
    ) 
    ON DUPLICATE KEY UPDATE `out` = 1
    

    This issue seems due to a bug in mysql version 4.1.7 which states that

    you can't update the same table which you use in the SELECT part
    

    see Here

    Not sure if this is the same version you are using as well.