Mysql 如何解决在单个大小写表达式中选择多个列的问题

我想知道是否有任何方法可以根据if语句的结果选择两列

到目前为止，我已经把不必要的东西减半了：

  ( SELECT IF(
               (SELECT g.id
                FROM users AS u
                INNER JOIN user_groups AS g ON (g.id = u.group_id)
                WHERE u.id = 2) >= 4,

               (SELECT p.action, p.id
                FROM permissions AS p
                WHERE p.required_points <=
                    (SELECT reputation
                     FROM users
                     WHERE id = 2)),

               (SELECT 0, 0)))

基本上，是否存在行为类似于if语句的多列操作数？如果是这样，我将如何实施它们。任何资源链接都将不胜感激

错误是：

1241-操作数应包含1列

整个sql查询：

(SELECT p1.action,
          p1.id
   FROM user_permissions AS u1
   INNER JOIN permissions AS p1 ON (p1.id = u1.action_id)
   WHERE u1.user_id = 2)
UNION
  (SELECT p2.action,
          p2.id
   FROM users AS u2
   INNER JOIN user_groups AS g ON (g.id = u2.group_id)
   INNER JOIN group_permissions AS gp ON (gp.group_id = g.id)
   INNER JOIN permissions AS p2 ON (p2.id = gp.action_id)
   WHERE u2.id = 2)
UNION
  ( SELECT IF(
               (SELECT g2.id
                FROM users AS u3
                INNER JOIN user_groups AS g2 ON (g2.id = u3.group_id)
                WHERE u3.id = 2) >= 4,
               (SELECT p3.action, p3.id
                FROM permissions AS p3
                WHERE p3.required_points <=
                    (SELECT reputation
                     FROM users
                     WHERE id = 2)),
               (SELECT 0, 0)))

---

哦，这基本上就是整个查询。这行不通：

SELECT IF( (SELECT g2.id
            FROM users u3 INNER JOIN
                 user_groups AS g2
                 ON g2.id = u3.group_id
            WHERE u3.id = 2) >= 4,
           (SELECT p3.action, p3.id
            FROM permissions AS p3
            WHERE p3.required_points <= (SELECT reputation FROM users WHERE id = 2)),
           (SELECT 0, 0)))

如果您确实不希望该行包含0，0，但它只是存在，因此存在其他值，那么让join或where将其过滤掉：

SELECT p3.action, p3.id
FROM (SELECT p3.action, p3.id
      FROM permissions AS p3
      WHERE p3.required_points <= (SELECT reputation FROM users WHERE id = 2))
     ) p3
WHERE (SELECT g2.id
       FROM users u3 INNER JOIN
            user_groups AS g2
            ON g2.id = u3.group_id
       WHERE u3.id = 2
      ) >= 4

---

你必须重复if语句。但是，如果你展示了你的全部查询或者简化的版本，可能有一种更简单的表达这个逻辑的方法。我确实考虑过，但是我不喜欢一个几乎完全复制的IF块的外观，所以假设必须有一个更好的方法。我现在就发布整个sql，希望能有所帮助。哦，谢谢，很抱歉回复太晚。我真的没有想过以这种方式使用子查询。

SELECT p3.action, p3.id
FROM (SELECT p3.action, p3.id
      FROM permissions AS p3
      WHERE p3.required_points <= (SELECT reputation FROM users WHERE id = 2))
     ) p3
WHERE (SELECT g2.id
       FROM users u3 INNER JOIN
            user_groups AS g2
            ON g2.id = u3.group_id
       WHERE u3.id = 2
      ) >= 4