Question

这是我的代码：

$sqlz = "SELECT t1.user_id, t2.status, t2.email 
         FROM coverages t1 
         LEFT JOIN users t2 ON t1.user_id = t2.user_id 
         GROUP BY t1.user_id  
         HAVING COUNT(t1.user_id) =".$value;

我想添加“WHERE users.email IS NOT NULL” 当我添加它时，它返回一个白页/没有结果。据我所知，db上至少有200个结果，其中包含一封电子邮件，并且符合该条件。

这是我所做的不起作用的一个例子：

 $sqlz =    "SELECT t1.user_id, t2.status, t2.email 
             FROM coverages t1 
             LEFT JOIN users t2 ON t1.user_id = t2.user_id
             WHERE users.email IS NOT NULL 
             GROUP BY t1.user_id  
             HAVING COUNT(t1.user_id) =".$value;

Answer 1

我认为您需要使用t2（别名）代替users。

 $sqlz =    "SELECT t1.user_id, t2.status, t2.email 
             FROM coverages t1 
                     LEFT JOIN users t2 ON t1.user_id = t2.user_id
             WHERE t2.email IS NOT NULL 
             GROUP BY t1.user_id  
             HAVING COUNT(t1.user_id) = " .$value;

mysql有和where子句在同一个查询上

1 个答案: