MySQL-5.7 存储过程及函数

1.语法

CREATE
    [DEFINER = { user | CURRENT_USER }]
    PROCEDURE sp_name ([proc_parameter[,...]])
    [characteristic ...] routine_body

CREATE
    [DEFINER = { user | CURRENT_USER }]
    FUNCTION sp_name ([func_parameter[,...]])
    RETURNS type
    [characteristic ...] routine_body

proc_parameter:
    [ IN | OUT | INOUT ] param_name type

func_parameter:
    param_name type

type:
    Any valid MySQL data type

characteristic:
    COMMENT 'string'
  | LANGUAGE SQL
  | [NOT] DETERMINISTIC
  | { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA }
  | SQL SECURITY { DEFINER | INVOKER }

routine_body:
    Valid SQL routine statement

参数详解：

（1）DEFINER

表示创建存储过程及函数的用户，默认为当前用户；

（2）func_parameter

表示存储过程的参数。在Create Procedure 语句中，可以声明一个或多个参数。当调用该存储过程时，用户必须给出所有的参数值，除非定义了参数的缺省值。若参数的形式以 @parameter=value 出现，则参数的次序可以不同，否则用户给出的参数值必须与参数列表中参数的顺序保持一致。若某一参数以@parameter=value 形式给出，那么其它参数也必须以该形式给出。一个存储过程至多有1024 个参数。

（3）characteristic

• LANGUAGE SQL:表示此存储过程和函数的创建语言；
• [NOT] DETERMINISTIC:表明输入相同的参数会返回相同的结果，反之表示相同的参数不会是相同的结果，默认是not deterministic；
• -- CONTAINS SQL :子程序不包含读或写数据的语句；
• -- NO SQL : 子程序不包含SQL语句；
• -- READS SQL DATA :子程序包含读数据的语句；
• -- MODIFIES SQL DATA : 子程序包含写数据的语句；
• -- 如果这些特征没有明确给定，默认的是CONTAINS SQL；

（4）SQL SECURITY { DEFINER | INVOKER }

子程序该用创建子程序者的许可来执行，还是使用调用者的许可来执行。默认值是DEFINER。

（5）COMMENT

是一个MySQL的扩展，它可以被用来描述存储程序。这个信息被SHOW CREATE PROCEDURE和 SHOW CREATE FUNCTION语句来显示。

2.存储过程与函数特性

（1）存储过程与函数的区别

• 函数调用有返回值
• 存储过程调用用call语句，函数调用直接饮用函数名+参数

（2）Definer和sql security

• Definder是MySQL的特殊访问控制手段，当数据库当前没有这个用户权限时，执行存储过程可能会报错；
• sql security的值决定了调用存储过程的方式，取值：definer（默认）或invoker；
• definer在执行时先验证definer对应的用户，如：cdq@127.0.0.1是否存在，以及是否具有执行存储过程的权限，若没有则报错；
• invoker在执行存储过程时判断invoker，即调用该存储过程的用户是否有相应权限，若没有则报错

（3）IN，OUT，INOUT

只适用于存储过程，对函数而言所有参数默认都是输入参数

• IN用于把数值传入到存储过程中
• OUT用于输出参数将数值传递给调用者
• INOUT输入输出参数把数据传入到存储过程，在存储过程中修改后再传递给调用者

3.实例演示

（1）简单存储过程

mysql> delimiter //
mysql> create procedure simpleproc(in param1 int,out param2 int)
    -> begin
    -> select count(*) into param2 from students where sid > param1;
    -> end//
Query OK, 0 rows affected (0.02 sec)

mysql> delimiter ;
mysql> call simpleproc(1,@a);
Query OK, 1 row affected (0.00 sec)

mysql> select @a;
+------+
| @a   |
+------+
|    7 |
+------+
1 row in set (0.00 sec)

说明：

• delimiter命令是改变语句的结束符，MySQL默认结束符为；号，由于存储过程和函数中的；号并不代表结束，所以要替换另外的结束符；

（2）简单的函数

mysql> create function hello(s char(20))
    -> returns char(50)
    -> return concat('Hello',s,'!');
Query OK, 0 rows affected (0.00 sec)

mysql> select hello('world');
+----------------+
| hello('world') |
+----------------+
| Helloworld!    |
+----------------+
1 row in set (0.00 sec)

（3）复杂的示例

mysql> delimiter //
mysql> create function simplefunc(param1 int)
    -> returns int
    -> begin
    -> update students set gender=1 where sid=param1;
    -> select count(*) into @a from students where sid > param1;
    -> return @a;
    -> end//
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
mysql> select * from students where sid=1;
+-----+--------+--------+---------+
| sid | sname  | gender | dept_id |
+-----+--------+--------+---------+
|   1 | Andrew | 0      |       1 |
+-----+--------+--------+---------+
1 row in set (0.00 sec)

mysql> select simplefunc(1);
+---------------+
| simplefunc(1) |
+---------------+
|             7 |
+---------------+
1 row in set (0.03 sec)

mysql> select * from students where sid=1;
+-----+--------+--------+---------+
| sid | sname  | gender | dept_id |
+-----+--------+--------+---------+
|   1 | Andrew | 1      |       1 |
+-----+--------+--------+---------+
1 row in set (0.01 sec)

说明：

• MySQL存储过程和函数中也可以包含类似create和drop等DDL语句；
• rontine_body子句可以包含一个简单的SQL语句，也可以包含多个SQL语句，通过begin...end将多个SQL语句包含在一起；

4.测试definer

[root@localhost ~]# mysql -uabc2 -p
Enter password: 

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| course             |
+--------------------+
2 rows in set (0.01 sec)

mysql> use course;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> delimiter //
mysql> create procedure simpleproc2(IN param1 int,out param2 int)
    -> begin
    -> select count(*) into param2 from students where sid > param1;
    -> end//
Query OK, 0 rows affected (0.00 sec)

[root@localhost ~]# mysql -p
Enter password: 

mysql> use course;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> call simpleproc2(1,@a);
Query OK, 1 row affected (0.00 sec)

mysql> drop user 'abc2'@'localhost';
Query OK, 0 rows affected (0.00 sec)

mysql> call simpleproc2(1,@a);
ERROR 1449 (HY000): The user specified as a definer ('abc2'@'localhost') does not exist

查看存储过程及函数的相关数据库信息（在information_schema库）
mysql> select ROUTINE_SCHEMA,ROUTINE_NAME,ROUTINE_TYPE,ROUTINE_BODY,ROUTINE_DEFINITION,DEFINER from ROUTINES where ROUTINE_SCHEMA = 'course';
+----------------+--------------+--------------+--------------+-------------------------------------------------------------------------------------------------------------------------------+----------------+
| ROUTINE_SCHEMA | ROUTINE_NAME | ROUTINE_TYPE | ROUTINE_BODY | ROUTINE_DEFINITION                                                                                                            | DEFINER        |
+----------------+--------------+--------------+--------------+-------------------------------------------------------------------------------------------------------------------------------+----------------+
| course         | hello        | FUNCTION     | SQL          | return concat('Hello',s,'!')                                                                                                  | root@localhost |
| course         | simplefunc   | FUNCTION     | SQL          | begin
update students set gender=1 where sid=param1;
select count(*) into @a from students where sid > param1;
return @a;
end | root@localhost |
| course         | simpleproc   | PROCEDURE    | SQL          | begin
select count(*) into param2 from students where sid > param1;
end                                                       | root@localhost |
| course         | simpleproc2  | PROCEDURE    | SQL          | begin
select count(*) into param2 from students where sid > param1;
end                                                       | abc2@localhost |
+----------------+--------------+--------------+--------------+-------------------------------------------------------------------------------------------------------------------------------+----------------+

mysql> alter procedure simpleproc2 sql security invoker;
Query OK, 0 rows affected (0.00 sec)

mysql> call simpleproc2(1,@a);
Query OK, 1 row affected (0.00 sec)

说明：

相关属性短语只有咨询含义，并不是强制性约束

• contains sql表明此存储过程或函数不包含读或者写数据的语句，这是默认属性；
• no sql表明此存储过程或函数不包含SQL语句
• reads sql data表示此存储过程包含诸如select的查询数据的语句，但不包含插入或删除数据的语句
• modifies sql data表示存储过程包含插入或删除数据的语句

5.删除语句

DROP {procedure | function} {IF EXISTS} sp_name;

if exists用来避免在删除一个本身不存在的存储过程或函数时，MySQL返回错误；

mysql> drop procedure oldboy;
ERROR 1305 (42000): PROCEDURE course.oldboy does not exist
mysql> drop procedure if exists oldboy;
Query OK, 0 rows affected, 1 warning (0.00 sec)

6.查看存储过程及函数

mysql> show create procedure simpleproc;
+------------+-------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
| Procedure  | sql_mode                                                                                                                                  | Create Procedure                                                                                                                                               | character_set_client | collation_connection | Database Collation |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
| simpleproc | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION | CREATE DEFINER=`root`@`localhost` PROCEDURE `simpleproc`(in param1 int,out param2 int)
begin
select count(*) into param2 from students where sid > param1;
end | utf8                 | utf8_general_ci      | latin1_swedish_ci  |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+

mysql> show create function simplefunc;
+------------+-------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
| Function   | sql_mode                                                                                                                                  | Create Function                                                                                                                                                                                                   | character_set_client | collation_connection | Database Collation |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
| simplefunc | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION | CREATE DEFINER=`root`@`localhost` FUNCTION `simplefunc`(param1 int) RETURNS int(11)
begin
update students set gender=1 where sid=param1;
select count(*) into @a from students where sid > param1;
return @a;
end | utf8                 | utf8_general_ci      | latin1_swedish_ci  |
+------------+-------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+
1 row in set (0.01 sec)