Question

我需要使用来自两个不同表格的数据创建一个视图。

我试过这个：

CREATE VIEW `moviesdatastore`.`view_user_group` AS
SELECT user_name FROM tbl_spj_user, 
SELECT group_name FROM tbl_spj_group;

但这会导致：

ERROR 1349: View's SELECT contains a subquery in the FROM clause

看不到子查询在哪里.....

如何从两个不同的表中创建数据视图？我在我的java Web应用程序上需要它用于JAAS。

Answer 1

您可以使用union

CREATE VIEW `moviesdatastore`.`view_user_group` AS
(
  SELECT user_name AS name FROM tbl_spj_user
)
UNION ALL
(
  SELECT group_name AS name FROM tbl_spj_group;
)

请注意，您不会知道哪些条目来自组，哪些条目来自用户。如果您需要对其进行区分，请使用类型向视图添加另一列，例如：

CREATE VIEW `moviesdatastore`.`view_user_group` AS
(
  SELECT user_name AS name, 'user' AS type FROM tbl_spj_user
)
UNION ALL
(
  SELECT group_name AS name, 'group' AS type FROM tbl_spj_group;
)

Answer 2

如果你可以加入表格，那么加入应该比联盟更好

CREATE VIEW  `moviesdatastore`.`view_user_group` AS 
SELECT 
user_name 
FROM tbl_spj_user 
INNER JOIN tbl_spj_group ON tbl_spj_group.groupID=tbl_spj_user.groupID

Answer 3

可能是你想要的连接。

CREATE VIEW `moviesdatastore`.`view_user_group` AS
SELECT A.user_name, B.group_name 
FROM tbl_spj_user A
LEFT JOIN tbl_spj_group B ON A.group_id = B.id;

MySQL View包含两个表中的数据

3 个答案: