Question

SELECT ser_id
FROM services
WHERE name = "office_small"
AND pr_id = (
            SELECT pr_id
            FROM profile
            WHERE pr_name  like ( SELECT sel_profile
                                 FROM customer
                                 WHERE id =443
                                )
              )

嗨，每一个我在MySQL中使用上层查询但是它返回零行但是当我在in子句中使用它时它会返回正确的结果，所以如果对内部查询有任何限制使用吗？感谢

Answer 1

尝试运行上一次的查询

1.SELECT sel_profile  FROM customer  WHERE id =443 =OUTPUT
2.(SELECT pr_id FROM profile  WHERE pr_name  like =OUTPUT) =OUTPUT2
3.(SELECT ser_id FROM services WHERE name = "office_small" AND pr_id = OUTPUT2) =OUTPUT3

如果您得到了正确的结果，那么您就是正确的路径，否则可能会出现与数据库表相关的问题

Answer 2

1.SELECT sel_profile  FROM customer  WHERE id =443 =OUTPUT
2.(SELECT pr_id FROM profile  WHERE pr_name  like '%OUTPUT%') =OUTPUT2
3.(SELECT ser_id FROM services WHERE name = "office_small" AND pr_id = OUTPUT2) =OUTPUT3

像MySQL中的内部查询的运算符不起作用

2 个答案: