dongyuxin5353 2014-07-24 13:48
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mysql select union不起作用

Mysql version 5.1. Code example:

mysql_query("SELECT * FROM abonents WHERE `session_id`='$current_sess_id' UNION SELECT * FROM abonents_problem WHERE `session_id`='$current_sess_id' UNION SELECT * FROM abonents_stop WHERE `session_id`='$current_sess_id'");

Runs if remove "UNION", example:

mysql_query("SELECT * FROM abonents WHERE `session_id`='$current_sess_id'" );

"WTF Code" forever =):

$rez_11_one = mysql_query(
        "SELECT * FROM abonents WHERE `session_id`='$current_sess_id'"
    );
    $rez_11_two = mysql_query(
        "SELECT * FROM abonents_problem WHERE `session_id`='$current_sess_id'"
    );
    $rez_11_three = mysql_query(
        "SELECT * FROM abonents_stop WHERE `session_id`='$current_sess_id'"
    );
    if ($rez_11_one) {
        $rez_11 = $rez_11_one;
    } elseif ($rez_11_two) {
        $rez_11 = $rez_11_two;
    } else {
        $rez_11 = $rez_11_three;
    }

Thank's for help

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4条回答 默认 最新

  • duanaoyuan7202 2014-07-24 13:50
    关注

    reference to the mysql documentation UNION only works if all querys return the same number of columns.

    http://dev.mysql.com/doc/refman/4.1/en/union.html

    therefore as you use a selector asterisks * i think the tables have a different amount of columns. use select eg

    SELECT 1,2 FROM foo UNION SELECT 1,2 FROM bar

    to get per query the same amount of columns.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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