三十七.MySQL视图 MySQL存储过程
1.视图的基本使用
把/etc/passwd文件的内容存储到db9库下的user表里
添加新字段id 存储记录的行号(在所有字段的前边)
创建视图v1 结构及数据user表的字段、记录一样。
创建视图v2 只有user表shell是/bin/bash用户信息 。
分别对视图表和基表执行insert update delete 操作。
删除视图v1 和 v2
什么是视图：是一种虚拟存在的表
内容与真实的表相似，包含一系列带有名称的列和行数据。
视图并不在数据库中以存储的数据的形式存在。
行和列的数据来自定义视图时查询所引用的基本表，并且在具体引用视图时动态生成。
更新视图的数据，就是更新基表的数据
更新基表数据，视图的数据也会跟着改变
1.1 把/etc/passwd文件的内容存储到db9库下的user表里
mysql> CREATE DATABASE db9;
mysql> create table db9.user(username char(20),password char(1),uid \
int(2),gid int(2),comment char(100),homedir char(100),shell char(50));
//创建存储数据的表结构
ysql> DESC user;
+----------+-----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-----------+------+-----+---------+-------+
| username | char(20) | YES | | NULL | |
| password | char(1) | YES | | NULL | |
| uid | int(2) | YES | | NULL | |
| gid | int(2) | YES | | NULL | |
| comment | char(100) | YES | | NULL | |
| homedir | char(100) | YES | | NULL | |
| shell | char(50) | YES | | NULL | |
+----------+-----------+------+-----+---------+-------+
mysql> system cp /etc/passwd /var/lib/mysql-files/
mysql> system ls /var/lib/mysql-files/
passwd
mysql> load data infile "/var/lib/mysql-files/passwd" into table db9.user \
-> fields terminated by ":" lines terminated by "\n";
1.2 添加新字段id 存储记录的行号(在所有字段的前边)
mysql> alter table db9.user add id int(2) primary key auto_increment first;
1.3 创建视图v1 结构及数据user表的字段、记录一样
mysql> create view v1 as select * from user;
mysql> select * from v1;
1.4 创建视图v2 只有user表shell是/bin/bash用户信息
mysql> create view v2 as select shell from user where shell="/bin/bash";
mysql> select * from v2;
1.5 分别对视图表和基表执行insert update delete 操作
mysql> insert into v1(username,uid) values("jarry",9); //插入记录
mysql> update v1 set uid=9 where username="adm"; //更新记录
mysql> delete from v1 where uid=9; //删除记录
1.6 删除视图v1 和 v2
mysql> drop view v1;
mysql> drop view v2;
2. 视图进阶操作
练习OR REPLACE的选项使用
练习WITH LOCAL CHECK OPTION 选项的使用
练习WITH CASCADED CHECK OPTION 选项的使用
2.1 创建视图完全格式
mysql> create table user2 select username,uid,gid from user limit 3;
//快速建表（user2表）
mysql> select * from user2;
+----------+------+------+
| username | uid | gid |
+----------+------+------+
| root | 0 | 0 |
| bin | 1 | 1 |
| daemon | 2 | 2 |
+----------+------+------+
mysql> create table info select username,uid,homedir,shell from user limit 5;
//快速建表（info表）
mysql> select * from info;
+----------+------+----------------+---------------+
| username | uid | homedir | shell |
+----------+------+----------------+---------------+
| root | 0 | /root | /bin/bash |
| bin | 1 | /bin | /sbin/nologin |
| daemon | 2 | /sbin | /sbin/nologin |
| lp | 4 | /var/spool/lpd | /sbin/nologin |
| sync | 5 | /sbin | /bin/sync |
+----------+------+----------------+---------------+
2.2 查询user2.username(3)=info.username(4)的字段
mysql> select * from user2 left join info on user2.username=info.username;
+----------+------+------+----------+------+---------+---------------+
| username | uid | gid | username | uid | homedir | shell |
+----------+------+------+----------+------+---------+---------------+
| root | 0 | 0 | root | 0 | /root | /bin/bash |
| bin | 1 | 1 | bin | 1 | /bin | /sbin/nologin |
| daemon | 2 | 2 | daemon | 2 | /sbin | /sbin/nologin |
+----------+------+------+----------+------+---------+---------------+
2.3 关联查询建的视图 默认不允许修改视图字段的值
mysql> create view v4 as select a.username as ausername,b.username as busername,a.uid as auid,b.uid as buid from user2 a left join info b on a.username=b.username;
mysql> select * from v4;
+-----------+-----------+------+------+
| ausername | busername | auid | buid |
+-----------+-----------+------+------+
| root | root | 0 | 0 |
| bin | bin | 1 | 1 |
| daemon | daemon | 2 | 2 |
+-----------+-----------+------+------+
2.4 OR REPLACE的选项使用
创建时，若视图已存在，会替换已有的视图
语法格式：create or replace view视图名as select 查询； //达到修改已有视图的目的
mysql> create or replace view v4 as select a.username as ausername,b.username as busername,a.uid as auid,b.uid as buid from user2 a left join info b on a.username=b.username;
2.5 WITH LOCAL CHECK OPTION
LOCAL和CASCADED关键字决定检查的范围
LOCAL 仅检查当前视图的限制
CASCADED 同时要满足基表的限制（默认值）
mysql> create table user1 select username,uid,shell from user where uid>=5 and uid <=40;
mysql> select * from user1;
+----------+------+----------------+
| username | uid | shell |
+----------+------+----------------+
| sync | 5 | /bin/sync |
| shutdown | 6 | /sbin/shutdown |
| halt | 7 | /sbin/halt |
| mail | 8 | /sbin/nologin |
| operator | 11 | /sbin/nologin |
| games | 12 | /sbin/nologin |
| ftp | 14 | /sbin/nologin |
| rpc | 32 | /sbin/nologin |
| rpcuser | 29 | /sbin/nologin |
| ntp | 38 | /sbin/nologin |
| mysql | 27 | /bin/false |
+----------+------+----------------+
mysql> create view v1 as select username,uid from user1 where uid<=20;
mysql> select * from v1;
+----------+------+
| username | uid |
+----------+------+
| sync | 5 |
| shutdown | 6 |
| halt | 7 |
| mail | 8 |
| operator | 11 |
| games | 12 |
| ftp | 14 |
+----------+------+
mysql> update v1 set uid=21 where username="sync";
//操作超过视图表的条件限制（uid<=20）之后，在视图表里面查看不到，在基表里可以查看到
也就是说，更新视图表数据会直接更改基表数据；更新视图表数据超出视图限制，会修改成功，但是会被限制在要求之外。
mysql> update user1 set uid=41 where username="ftp";
//基表在超过条件限制（uid>=5 and uid <=40),在基表里依然可以查看到
也就是说，基表随便修改都能成功
mysql> select * from user1;
+----------+------+----------------+
| username | uid | shell |
+----------+------+----------------+
| sync | 5 | /bin/sync |
| shutdown | 6 | /sbin/shutdown |
| halt | 7 | /sbin/halt |
| mail | 8 | /sbin/nologin |
| operator | 11 | /sbin/nologin |
| games | 12 | /sbin/nologin |
| ftp | 41 | /sbin/nologin |
| rpc | 32 | /sbin/nologin |
| rpcuser | 29 | /sbin/nologin |
| ntp | 38 | /sbin/nologin |
| mysql | 27 | /bin/false |
+----------+------+----------------+
v1里面没有，ftp移除
也就是说，修改基表数据，会直接影响视图数据，
进而说明，视图数据是动态生成，数据来源相当于于查询基表数据时产生的动态缓存。
mysql> select * from v1;
+----------+------+
| username | uid |
+----------+------+
| sync | 5 |
| shutdown | 6 |
| halt | 7 |
| mail | 8 |
| operator | 11 |
| games | 12 |
+----------+------+
mysql> create table a select * from user where uid < 10;
//快速创建一个新表a
mysql> select * from a;
+----+----------+----------+------+------+----------+-----------------+----------------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+----------+-----------------+----------------+
| 1 | root | x | 0 | 0 | root | /root | /bin/bash |
| 2 | bin | x | 1 | 1 | bin | /bin | /sbin/nologin |
| 3 | daemon | x | 2 | 2 | daemon | /sbin | /sbin/nologin |
| 5 | lp | x | 4 | 7 | lp | /var/spool/lpd | /sbin/nologin |
| 6 | sync | x | 5 | 0 | sync | /sbin | /bin/sync |
| 7 | shutdown | x | 6 | 0 | shutdown | /sbin | /sbin/shutdown |
| 8 | halt | x | 7 | 0 | halt | /sbin | /sbin/halt |
| 9 | mail | x | 8 | 12 | mail | /var/spool/mail | /sbin/nologin |
+----+----------+----------+------+------+----------+-----------------+----------------+
mysql> create view v3 as select * from a where uid < 10 with check option;
//不写默认为CASCADED检查自己和a要满足的要求即可
mysql> select * from v3;
+----+----------+----------+------+------+----------+-----------------+----------------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+----------+-----------------+----------------+
| 1 | root | x | 0 | 0 | root | /root | /bin/bash |
| 2 | bin | x | 1 | 1 | bin | /bin | /sbin/nologin |
| 3 | daemon | x | 2 | 2 | daemon | /sbin | /sbin/nologin |
| 5 | lp | x | 4 | 7 | lp | /var/spool/lpd | /sbin/nologin |
| 6 | sync | x | 5 | 0 | sync | /sbin | /bin/sync |
| 7 | shutdown | x | 6 | 0 | shutdown | /sbin | /sbin/shutdown |
| 8 | halt | x | 7 | 0 | halt | /sbin | /sbin/halt |
| 9 | mail | x | 8 | 12 | mail | /var/spool/mail | /sbin/nologin |
+----+----------+----------+------+------+----------+-----------------+----------------+
mysql> update v3 set uid=9 where username="bin"; //更改成功
mysql> update v3 set uid=11 where username="bin";
ERROR 1369 (HY000): CHECK OPTION failed 'db9.v3'
mysql> create view v2 as select * from v1 where uid >= 5 with local check option;
//满足自身v2的要求
mysql> select * from v2;
+----------+------+
| username | uid |
+----------+------+
| sync | 5 |
| shutdown | 6 |
| halt | 7 |
| mail | 8 |
| operator | 11 |
| games | 12 |
+----------+------+
mysql> update v2 set uid=9 where username="sync";
mysql> select * from v2;
+----------+------+
| username | uid |
+----------+------+
| sync | 9 |
| shutdown | 6 |
| halt | 7 |
| mail | 8 |
| operator | 11 |
| games | 12 |
+----------+------+
mysql> select * from v1;
+----------+------+
| username | uid |
+----------+------+
| sync | 9 |
| shutdown | 6 |
| halt | 7 |
| mail | 8 |
| operator | 11 |
| games | 12 |
+----------+------+
mysql> select * from user1;
+----------+------+----------------+
| username | uid | shell |
+----------+------+----------------+
| sync | 9 | /bin/sync |
| shutdown | 6 | /sbin/shutdown |
...
2.6 WITH CASCADED CHECK OPTION
mysql> create view v5 as select * from v1 where uid >= 5 with cascaded check option;
mysql> select * from v5;
+----------+------+
| username | uid |
+----------+------+
| sync | 9 |
| shutdown | 6 |
| halt | 7 |
| mail | 8 |
| operator | 11 |
| games | 12 |
+----------+------+
3.创建存储过程
存储过程名称为p1
功能显示user表中 shell是/bin/bash的用户个数
调用存储过程p1
3.1 创建存储过程
mysql> delimiter // //定义定界符
mysql> create procedure say() //say随便写括号一定要有
-> begin
-> select * from user where id<=10;
-> end
-> //
mysql> delimiter ; //把命令的定界符改回来，分号前有空格
mysql> call say(); //调用存储过程名,在括号里面不写参数时，可以不加括号
+----+----------+----------+------+------+----------+-----------------+----------------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+----------+-----------------+----------------+
| 1 | root | x | 0 | 0 | root | /root | /bin/bash |
| 2 | bin | x | 1 | 1 | bin | /bin | /sbin/nologin |
| 3 | daemon | x | 2 | 2 | daemon | /sbin | /sbin/nologin |
| 5 | lp | x | 4 | 7 | lp | /var/spool/lpd | /sbin/nologin |
| 6 | sync | x | 5 | 0 | sync | /sbin | /bin/sync |
| 7 | shutdown | x | 6 | 0 | shutdown | /sbin | /sbin/shutdown |
| 8 | halt | x | 7 | 0 | halt | /sbin | /sbin/halt |
| 9 | mail | x | 8 | 12 | mail | /var/spool/mail | /sbin/nologin |
| 10 | operator | x | 11 | 0 | operator | /root | /sbin/nologin |
+----+----------+----------+------+------+----------+-----------------+----------------+
创建存储过程名称为p1
功能显示user表中 shell是/bin/bash的用户
调用存储过程p1
mysql> delimiter //
mysql> create procedure p1()
-> begin
-> select count(username) from user where shell="/bin/bash";
-> end
-> //
mysql> delimiter ;
mysql> call p1();
+-----------------+
| count(username) |
+-----------------+
| 2 |
+-----------------+
mysql> select username from user where shell="/bin/bash";
+----------+
| username |
+----------+
| root |
| student |
+----------+
查看存储过程
方法一：
mysql> show procedure status\G;
方法二：
mysql> select db,name,type from mysql.proc where name= "say";
+-----+------+-----------+
| db | name | type |
+-----+------+-----------+
| db9 | say | PROCEDURE |
+-----+------+-----------+
3.3 删除存储过程
mysql> drop procedure say;
3.4 查看已有过程
mysql> select db,name,type from mysql.proc;
4. 存储过程参数的使用
参数类型
MySQL存储过程，共有三种参数类型IN,OUT,INOUT
Create procedure 名称(
类型 参数名 数据类型,
类型 参数名 数据类型
）
in输入参数 传递值给存储过程，必须在调用存储过程时指定，在存储过程中不能修改该参数的值；默认类型是in
out输出参数该值可在存储过程内部被改变，并可返回
inout输入/输出参数调用时指定，并且可被改变和返回
案例1：
mysql> delimiter //
mysql> create procedure say2(in name char(10))
-> begin
-> select name;
-> select * from user where username=name;
-> end
-> //
mysql> delimiter ;
mysql> call say2("ftp");
+------+
| name |
+------+
| ftp |
+------+
+----+----------+----------+------+------+----------+----------+---------------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+----------+----------+---------------+
| 12 | ftp | x | 14 | 50 | FTP User | /var/ftp | /sbin/nologin |
+----+----------+----------+------+------+----------+----------+---------------+
案例2：
mysql> delimiter //
mysql> create procedure p2(out number int)
-> begin
-> select count(username) into @number from user where shell!="/bin/bash";
-> select @number;
-> end
-> //
mysql> delimiter ;
mysql> call p2(@number);
+---------+
| @number |
+---------+
| 39 |
+---------+
5.使用循环结构
5.1 算数运算
mysql> set @z=1+2;select @z;
+------+
| @z |
+------+
| 3 |
+------+
mysql> set @x=1; set @y=2;set @z=@x*@y; select @z;
+------+
| @z |
+------+
| 2 |
+------+
mysql> set @x=1; set @y=2;set @z=@x/@y; select @z;
+-------------+
| @z |
+-------------+
| 0.500000000 |
+-------------+
declare调用变量不需要@,其他都需要
调用变量时，有@符号的变量 如@x：调用的是用户自定义变量
没有@符号的变量 如x：调用的是存储过程的参数变量
mysql> delimiter //
mysql> create procedure say5(in bash char(20), in nologin char(25), out x int , out y int)
-> begin
-> declare z int ;
-> set z=0;
-> select count(username) into @x from user where shell=bash;
-> select count(username) into @y from user where shell=nologin;
-> set z=@x+@y;
-> select z;
-> end
-> //
mysql> delimiter ;
mysql> call say5("/bin/bash","/sbin/nologin",@x,@y);
+------+
| z |
+------+
| 36 |
+------+
mysql> delimiter //
mysql> create procedure say6(in bash char(20),in nologin char(25),out x int ,out y int)
-> begin
-> declare z int ;
-> set z=0;
-> select count(username) into @x from user where shell=bash;
-> select count(username) into @y from user where shell=nologin;
-> set z=@x+@y;
-> select z;
-> end
-> //
mysql> delimiter ;
mysql> call say6("/bin/bash","/sbin/nologin",@x,@y);
+------+
| z |
+------+
| 36 |
+------+
5.2 条件判断，数值的比较如图-2所示：
5.3 逻辑比较、范围、空、非空、模糊、正则，如图-3所示：
顺序结构（if判断）当“条件成立”时执行命令序列,否则，不执行任何操作
mysql> delimiter //
mysql> create procedure say7(in x int(1) )
-> begin
-> if x <= 10 then
-> select * from user where id <=x;
-> end if;
-> end
-> //
mysql> delimiter ;
mysql> call say7(1); //条件判断成立，等于1是否成立
+----+----------+----------+------+------+---------+---------+-----------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+---------+---------+-----------+
| 1 | root | x | 0 | 0 | root | /root | /bin/bash |
+----+----------+----------+------+------+---------+---------+-----------+
mysql> mysql> call say7(2);
+----+----------+----------+------+------+---------+---------+---------------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+---------+---------+---------------+
| 1 | root | x | 0 | 0 | root | /root | /bin/bash |
| 2 | bin | x | 1 | 1 | bin | /bin | /sbin/nologin |
+----+----------+----------+------+------+---------+---------+---------------+
mysql> delimiter //
mysql> create procedure p3(in linenum char(10) )
-> begin
-> if linenum is null then
-> set @linenum=1;
-> select * from user where id=@linenum;
-> else
-> select linenum;
-> select * from user where id=linenum;
-> end if;
-> end
-> //
mysql> delimiter ;
mysql> call p3(null); //不输入查看的行数
+----+----------+----------+------+------+---------+---------+-----------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+---------+---------+-----------+
| 1 | root | x | 0 | 0 | root | /root | /bin/bash |
+----+----------+----------+------+------+---------+---------+-----------+
mysql> call p3(3);
+---------+
| linenum |
+---------+
| 3 |
+---------+
+----+----------+----------+------+------+---------+---------+---------------+
| id | username | password | uid | gid | comment | homedir | shell |
+----+----------+----------+------+------+---------+---------+---------------+
| 3 | daemon | x | 2 | 2 | daemon | /sbin | /sbin/nologin |
+----+----------+----------+------+------+---------+---------+---------------+
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