php - MySQL:如何从表中获取具有指定值的某些列？

Question

我有 2 个表，分别名为learning_plan 和 tbl_user。我想这样做:

$qry=Query("SELECT user_name,user_family,coach_code FROM tbl_user WHERE user_level=2");
    while($result=mysql_fetch_array($qry))
     {
       $qry1=Query("SELECT * FROM learning_plan WHERE coach_code=".$result['coach_code']);
         while($result1=mysql_fetch_array($qry1))
           {

           }
     }

所以我想在第二个查询中获取具有这些值的列(!=1和<5)

非常感谢

Answer 1

为什么不只使用一个 JOIN 查询:？

 SELECT user_name,user_family,coach_code,t2.* 
 FROM tbl_user t1
 INNER JOIN learning_plan t2 ON t2.coach_code = t1.coach_code 
 WHERE t1.user_level=2