Question

我从用户那里获得一个输入，检查db中的值，如果正确则执行某些操作，如

    $getuser_key = $_POST['keyy'];

    $sql = "SELECT *  from demo_participant WHERE meeting_id_id IN(SELECT id FROM demo_meeting WHERE meetingID = '$get_meetingid') and `key` = '$get_meetinkey'";
    mysql_real_escape_string($sql);
    $result = mysql_query($sql) or die (mysql_error());
    while ($row = mysql_fetch_array($result)) {

          somthing 

           }

我可以使用union运算符吗？

现在我想要如果上面的查询失败，那么在另一个表中搜索$getuser_key

我只是想知道这是否可能，如果是这样的话呢？

Answer 1

JOIN他们：

 SELECT *  
 from demo_participant dp
 INNER JOIN demo_meeting dm ON dp.meetingID = dm.meetingID 
        AND dm.Key = '$get_meetinkey'
 INNER JOIN demo_thirdTable dt ON -- Somecondition here
 WHERE dp.key = '$get_meetinkey'

Mysql＆amp; PHP：在不同的mysql表中搜索

1 个答案: