mysql 存储过程简单学习

http://blog.chinaunix.net/uid-23302288-id-3785111.html

■存储过程Stored Procedure

存储过程就是保存一系列SQL命令的集合，将这些sql命令有组织的形成一个小程序，这样会实现很复杂的处理

SQL基本是一个命令一个命令执行，虽然可以通过连接、子查询等实现些高级的处理，但局限性是显而易见的

■存储过程的优势

1.提高执行性能(存储过程事先完成了解析、编译的处理，执行时能减轻数据库负担)

2.可减轻网络负担(比起多次传递SQL命令本身，这大大减轻了网络负担)

3.可防止对表的直接访问(可只赋予用户对相关存储过程的访问权限)

4.存储过程会保存在数据库中，应用程序只需要知道调用哪个存储过程就可以完成相应处理

■使用存储过程

参数种类分为: IN(输入型)，OUT(输出型)， INOUT(输入输出型)

SELECT column1.. INTO 变量1... FROM table1 WHERE xxx; //这个变量1对应OUT，INOUT

create procedure 存储过程名(

参数种类1 参数1 参数类型1

参数种类2 参数2 参数类型2...）

begin

处理内容

end

DELIMITER //

CREATE PROCEDURE search_customer(

IN p_nam VARCHAR(20))

BEGIN

IF p_nam IS NULL OR p_nam = '' THEN

SELECT * FROM customer;

ELSE

SELECT * FROM customer WHERE nam LIKE p_nam;

END IF;

END

//

DELIMITER ；

■注意事项

1.DELIMITER命令改变分隔符

默认分隔符是';' 存储过程中肯定会有';' ,所以使用其将分隔符改为'//' , 创建好后，在将分隔符改回';'

2.可使用的控制语句

IF语句

IF situation=1 THEN

command1;

ELSEIF situation=2 THEN

command2;

ELSE

command3;

END IF ;

CASE语句

CASE situation

WHEN 1 THEN command1;

WHEN 2 THEN command2;

WHEN 3 THEN command3;

ELSE command4;

END CASE;

WHILE (前置判断) 根据条件，循环有可能一次不执行

WHILE situation >1 DO

command1;

END WHILE;

REPEAT (后置判断) 不论条件如何，循环至少会执行一次 command1

REPEAT

command1;

UNTIL situation<=1 END REPEAT;

3.查看创建的存储过程状态

SHOW PROCEDURE STATUS \G;

SHOW CREATE PROCEDURE search_nam \G;

4.删除存储过程

DROP PROCEDURE search_nam;

5.执行存储过程

CALL search_nam('li%');

CALL search_nam('');

创建存储函数

mysql> DELIMITER //
mysql> CREATE PROCEDURE search_nam(
-> IN p_nam VARCHAR(20))
-> BEGIN
-> IF p_nam IS NULL OR p_nam='' THEN
-> SELECT * FROM USER3;
-> ELSE
-> SELECT * FROM USER3 WHERE name LIKE p_nam;
-> END IF;
-> END
-> //
Query OK, 0 rows affected (0.05 sec)

mysql> DELIMITER ;
查看创建的存储函数语句
mysql> SHOW CREATE PROCEDURE search_nam \G;
*************************** 1. row ***************************
Procedure: search_nam
sql_mode:
Create Procedure: CREATE DEFINER=`root`@`localhost` PROCEDURE `search_nam`(
IN p_nam VARCHAR(20))
BEGIN
IF p_nam IS NULL OR p_nam='' THEN
SELECT * FROM USER3;
ELSE
SELECT * FROM USER3 WHERE name LIKE p_nam;
END IF;
END
1 row in set (0.00 sec)
查看创建的存储函数状态

mysql> SHOW PROCEDURE STATUS \G;
*************************** 1. row ***************************
Db: test
Name: search_nam
Type: PROCEDURE
Definer: root@localhost
Modified: 2011-08-13 05:40:12
Created: 2011-08-13 05:40:12
Security_type: DEFINER
Comment:
1 row in set (0.00 sec)

调用存储过程 成功

mysql> CALL search_nam('aa%');
+------+------+
| id | name |
+------+------+
| 1 | aaa |
+------+------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)

mysql> CALL search_nam('');
+------+------+
| id | name |
+------+------+
| 1 | aaa |
| 2 | bbb |
| 3 | ccc |
+------+------+
3 rows in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)

演示OUT类型参数

mysql> DELIMITER //
mysql> CREATE PROCEDURE search_nam2(
-> IN p_nam VARCHAR(20),
-> OUT p_num INT)
-> BEGIN
-> IF p_nam IS NULL OR p_nam='' THEN
-> SELECT * FROM user3;
-> ELSE
-> SELECT * FROM USER3 WHERE name LIKE p_nam;
-> END IF;
-> SELECT FOUND_ROWS() INTO p_num;
-> END
-> //

mysql> DELIMITER ;

mysql> SHOW PROCEDURE STATUS ;
+------+-------------+-----------+----------------+---------------------+---------------------+
| Db | Name | Type | Definer | Modified | Created |
+------+-------------+-----------+----------------+---------------------+---------------------+
| test | search_nam | PROCEDURE | root@localhost | 2011-08-13 05:40:12 | 2011-08-13 05:40:12 |
| test | search_nam2 | PROCEDURE | root@localhost | 2011-08-13 05:56:37 | 2011-08-13 05:56:37 |
+------+-------------+-----------+----------------+---------------------+---------------------+
2 rows in set (0.00 sec)

调用成功

mysql> CALL search_nam3('bb%',@num);
+------+------+
| id | name |
+------+------+
| 2 | bbb |
+------+------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)
mysql> SELECT @num;
+------+
| @num |
+------+
| 1 |
+------+
1 row in set (0.00 sec)

IF多分枝演示

mysql> DELIMITER //
mysql> CREATE PROCEDURE depart(
-> IN de_nam VARCHAR(10))
-> BEGIN
-> IF de_nam=1 THEN
-> SELECT * FROM USER3 WHERE depart='IT';
-> ELSEIF de_nam=2 THEN
-> SELECT * FROM USER3 WHERE depart='HR';
-> ELSE
-> SELECT * FROM USER3 WHERE depart='BOSS';
-> END IF;
-> END
-> //
Query OK, 0 rows affected (0.00 sec)
mysql> DELIMITER ;

mysql> CALL depart(2); //演示成功
+------+------+--------+
| id | name | depart |
+------+------+--------+
| 2 | bbb | HR |
+------+------+--------+
1 row in set (0.00 sec)
CASE演示

mysql> DELIMITER //

mysql> CREATE PROCEDURE depart2(
-> IN de_num INT)
-> BEGIN
-> CASE de_num
-> WHEN 1 THEN
-> SELECT * FROM USER3 WHERE depart='IT';
-> WHEN 2 THEN
-> SELECT * FROM USER3 WHERE depart='HR';
-> ELSE
-> SELECT * FROM USER3 WHERE depart='BOSS';
-> END CASE;
-> END
-> //
Query OK, 0 rows affected (0.00 sec)
mysql> DELIMITER ;

mysql> CALL depart2(1);
+------+------+--------+
| id | name | depart |
+------+------+--------+
| 1 | aaa | IT |
+------+------+--------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec) //演示成功
mysql> CALL depart2(2);
+------+------+--------+
| id | name | depart |
+------+------+--------+
| 2 | bbb | HR |
+------+------+--------+
1 row in set (0.00 sec)

声明局部变量：
DECLARE tmp CHAR(10) [值]；
给变量赋值：
SET tmp='值' ;

mysql> DELIMITER //
mysql> CREATE PROCEDURE depart3(
-> IN p_num INT)
-> BEGIN
-> DECLARE tmp CHAR(5);
-> CASE p_num
-> WHEN 1 THEN
-> SET tmp='IT';
-> WHEN 2 THEN
-> SET tmp='HR';
-> ELSE
-> SET tmp='BOSS';
-> END CASE;

->
SELECT * FROM USER3 WHERE depart=tmp;

-> END
-> //

mysql> DELIMITER ;

mysql> call depart3(1);
+------+------+--------+
| id | name | depart |
+------+------+--------+
| 1 | aaa | IT |
+------+------+--------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql> call depart3(2); //调用成功
+------+------+--------+
| id | name | depart |
+------+------+--------+
| 2 | bbb | HR |
+------+------+--------+
1 row in set (0.00 sec)

演示while

mysql> DELIMITER //

mysql> CREATE PROCEDURE sp_sum(

-> IN p_num INT,

-> OUT res INT)

-> BEGIN

-> SET res=1;

-> WHILE p_num > 1 DO

-> SET res=res * p_num;

-> SET p_num=p_num - 1;

-> END WHILE;

-> END

-> //

Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;

mysql> CALL sp_sum(5,@res);

Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @res; //演示成功

+------+

| @res |

+------+

| 120 |

+------+

1 row in set (0.00 sec)

演示repeat

mysql> DELIMITER //
mysql> CREATE PROCEDURE sp_sum2(
-> IN p_num INT,
-> OUT res INT)
-> BEGIN
-> SET res = 1;
-> REPEAT
-> SET res=res * p_num;
-> SET p_num=p_sum - 1;
-> UNTIL p_num < 2 END REPEAT;
-> END
-> //

mysql> DELIMITER ;

mysql> CALL sp_sum2(5,@res);
Query OK, 0 rows affected (0.00 sec) //调用成功
mysql> SELECT @res;
+------+
| @res |
+------+
| 120 |
+------+
1 row in set (0.00 sec)