mysql有和where子句在同一个查询上

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;

我想添加这个" 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

我认为你需要使用t2(别名)而不是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;