MySQL视图介绍

创建数据库、导入数据

[root@localhost ~]# mysql -uroot -p -e"create database viewdb;"

Enter password:

[root@localhost ~]# mysql -uroot -p viewdb< viewdb.sql

Enter password:

mysql> show databases;

+--------------------+

| Database           |

+--------------------+

| information_schema |

| db2                |

| liujing            |

| mysql              |

| performance_schema |

| sys                |

| viewdb             |

| worlddb            |

| xiaowei            |

+--------------------+

9 rows in set (0.13 sec)

mysql> show tables;

+------------------+

| Tables_in_viewdb |

+------------------+

| user             |

| userinfo         |

+------------------+

2 rows in set (0.00 sec)

视图概述

视图是一个虚拟表，是从数据库中一个或多个表中导出来的表。视图还可以从已经存在的视图的基础上定义。

视图的作用

1、简化工作

2、提高安全性

3、逻辑独立

创建视图的语法

CREATE [OR REPLACE] [ALGORITHM] ={undefined|MERGE|TEMPTABLE}]

VIEW view_name [(column_list)]

AS SELECT_statement

[WITH[CASCADED|LOCAL] CHECK OPTION]

ALGORITHM用于设定视图的算法

CASCADED|LOCAL为限定条件。

CASCADED：默认值，更新时必须满足所有相关视图和表的条件。

LOCAL：更新时仅满足该视图本身定义的条件即可。

创建单表视图

mysql> create view view_user as selectname,age from user;

Query OK, 0 rows affected (0.01 sec)

查看

mysql> select name,age from user;

+---------+------+

| name   | age  |

+---------+------+

| TubeLiu |   10 |

| Kevin  |   20 |

| Mark   |   30 |

| July   |   40 |

+---------+------+

4 rows in set (0.00 sec)

mysql> select * from view_user;

+---------+------+

| name   | age  |

+---------+------+

| TubeLiu |   10 |

| Kevin  |   20 |

| Mark   |   30 |

| July   |   40 |

+---------+------+

4 rows in set (0.00 sec)

更新了视图中的数据

mysql> update view_user set age = 20where name=‘Tubeliu‘;

Query OK, 1 row affected (0.10 sec)

Rows matched: 1  Changed: 1 Warnings: 0

查看

mysql> select * from view_user;

+---------+------+

| name   | age  |

+---------+------+

| TubeLiu |   20 |

| Kevin  |   20 |

| Mark   |   30 |

| July   |   40 |

+---------+------+

4 rows in set (0.00 sec)

mysql> select name,age from user;

+---------+------+

| name   | age  |

+---------+------+

| TubeLiu |   20 |

| Kevin  |   20 |

| Mark   |   30 |

| July   |   40 |

+---------+------+

4 rows in set (0.00 sec)

对视图的操作也会影响真实表中的内容。

创建多表视图

mysql> create viewview_userinfo(name1,phone1) as select user.name,userinfo.phone fromuser,userinfo where id=fid;

Query OK, 0 rows affected (0.00 sec)

查看

mysql> select * from view_userinfo;

+---------+--------+

| name1  | phone1 |

+---------+--------+

| TubeLiu | 12345 |

| Kevin  |  54321 |

| Mark   |  32145 |

| July   |  34521 |

+---------+--------+

4 rows in set (0.00 sec)

mysql> select user.name,userinfo.phonefrom user,userinfo where id=fid;

+---------+-------+

| name   | phone |

+---------+-------+

| TubeLiu | 12345 |

| Kevin  | 54321 |

| Mark   | 32145 |

| July   | 34521 |

+---------+-------+

4 rows in set (0.00 sec)

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MySQL视图介绍

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