MySQL执行更多SQL语句并获得一个结果

Question

您好我想执行更多的SQL语句并获得一个结果，比如说我有3个表，它们都有相同的列名：

Table user1
User Password Email

Table user2
User Password Email

Table user3
User Password Email

现在我想从一个SQL语句中的所有表中获取所有用户密码电子邮件。我希望你能帮助我。

感谢您的帮助。

Answer 1

使用UNION。

SELECT User, PassWord, Email FROM Table1
UNION 
SELECT User, PassWord, Email FROM Table2
UNION 
SELECT User, PassWord, Email FROM Table3

以上查询将生成唯一记录。如果您想保留重复内容，请添加ALL

SELECT User, PassWord, Email FROM Table1
UNION ALL
SELECT User, PassWord, Email FROM Table2
UNION ALL
SELECT User, PassWord, Email FROM Table3

Answer 2

union将允许您合并记录集。

select user, password, email from user1
union 
select user, password, email from user2
union
select user, password, email from user3

Answer 3

很简单，使用Union运算符如下：

SELECT User, PassWord, Email FROM User1
UNION 
SELECT User, PassWord, Email FROM User2
UNION
SELECT User, PassWord, Email FROM User3

Answer 4

select User, Password, Email
from Table1
union all
select User, Password, Email
from Table2
union all
select User, Password, Email
from Table3

Answer 5

联盟行动是你问题的一个很好的例子：

select user, password, email from user1
union
selection user, password, email from user2
union
select user, password, email from user3