合并视图，以充当联合录制的单一表格

Question

我有几个表格如下所示：

+------------------------------------+
+ user_id | action_id | action_level +
+------------------------------------+
+ id_user | action_id | action_level +
+------------------------------------+

.

如何创建MySQL视图（或者也许有人可以建议更好地选择）这些将作为单个表：

+------------------------------------+
+ user_id | action_id | action_level +
+------------------------------------+

.

而不是加入它，这使得它如下所示：

+---------------------------------------------------------------------------------+
+ user_id | id_user | a_action_id | b_action_id | a_action_level | b_action_level +
+---------------------------------------------------------------------------------+

.

这样的方式，当我对表进行搜索时，我可以简单地搜索这样：

SELECT * FROM my_view WHERE action_id = 2;

.

Answer 1

Use a union

CREATE VIEW `user_actions` AS
SELECT a.user_id, a.action_id, a.action_level
UNION ALL
SELECT b.id_user AS user_id, b.action_id, b.action_level