一、MySQL存储过程_创建-调用
1.1存储过程:SQL中的“脚本”
1.创建存储过程
2.调用存储过程
3.存储过程体
4.语句标签块
二、MySQL存储过程简单介绍:
存储过程(Stored Procedure):
提示:#SQL语句:先编译后执行
一组可编程的函数,是为了完成特定功能的SQL语句集,经编译创建并保存在数据库中,用户可通过指定存储过程的名字并给定参数(需要时)来调用执行。
优点(为什么要用存储过程?):
①将重复性很高的一些操作,封装到一个存储过程中,简化了对这些SQL的调用
②批量处理:SQL+循环,减少流量,也就是“跑批”
③统一接口,确保数据的安全
相对于oracle数据库来说,MySQL的存储过程相对功能较弱,使用较少。
三、存储过程的创建和调用
说明:存储过程就是具有名字的一段代码,用来完成一个特定的功能。创建的存储过程保存在数据库的数据字典中。
3.1创建存储过程
语法介绍:
CREATE
[DEFINER = { user | CURRENT_USER }]
PROCEDURE sp_name ([proc_parameter[,...]])
[characteristic ...] routine_body
proc_parameter:
[ IN | OUT | INOUT ] param_name 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
[begin_label:] BEGIN
[statement_list]
……
END [end_label]
实例1演示:
创建测试表:
CREATE TABLE `test1_event` (
`id` int(8) NOT NULL AUTO_INCREMENT,
`username` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
`password` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
`create_time` varchar(20) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`id`) #主键ID
) ENGINE=innodb AUTO_INCREMENT=0 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
插入数据:
mysql> INSERT INTO test1_event(username,password,create_time) values(‘tomcat‘, ‘xiaohuahua‘,now());
Query OK, 1 row affected (0.00 sec)
mysql> INSERT INTO test1_event(username,password,create_time) values(‘tomcat‘, ‘xiaohuahua‘,now());
Query OK, 1 row affected (0.00 sec)
mysql> select * from test1_event;
+----+----------+------------+---------------------+
| id | username | password | create_time |
+----+----------+------------+---------------------+
| 1 | tomcat | xiaohuahua | 2018-09-12 17:18:01 |
| 2 | tomcat | xiaohuahua | 2018-09-12 17:18:39 |
| 3 | tomcat | xiaohuahua | 2018-09-12 17:18:45 |
+----+----------+------------+---------------------+
3 rows in set (0.00 sec)
#创建新表备份旧表的数据来用于示例操作:
mysql> create table test_event as select * from test.test1_event;
Query OK, 3 rows affected (0.04 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from test_event;
+----+----------+------------+---------------------+
| id | username | password | create_time |
+----+----------+------------+---------------------+
| 1 | tomcat | xiaohuahua | 2018-09-12 17:18:01 |
| 2 | tomcat | xiaohuahua | 2018-09-12 17:18:39 |
| 3 | tomcat | xiaohuahua | 2018-09-12 17:18:45 |
+----+----------+------------+---------------------+
3 rows in set (0.00 sec)
示例二:创建一个存储过程(给数据表中添加用户和密码并附加创建的时间)
DELIMITER // ### 将语句的结束符号从分号;临时改为两个//(可以是自定义)
DROP PROCEDURE IF EXISTS p_test1//
CREATE PROCEDURE p_test1()
BEGIN
INSERT INTO test_event(username,password,create_time) values(‘tomcat‘, ‘xiaohuahua‘,now());
END//
delimiter ; ####将语句的结束符号恢复为分号
查看创建的存储过程详细信息:
mysql> show procedure status;
+------+---------+-----------+----------------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+
| Db | Name | Type | Definer | Modified | Created | Security_type | Comment | character_set_client | collation_connection | Database Collation |
+------+---------+-----------+----------------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+
| test | p_test1 | PROCEDURE | [email protected] | 2018-09-12 17:44:40 | 2018-09-12 17:44:40 | DEFINER | | utf8 | utf8_general_ci | utf8_general_ci |
| test | p_test2 | PROCEDURE | [email protected] | 2018-09-07 18:25:54 | 2018-09-07 18:25:54 | DEFINER | | utf8 | utf8_general_ci | utf8_general_ci |
+------+---------+-----------+----------------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+
2 rows in set (0.00 sec)
删掉创建的存储过程:
mysql> drop procedure p_test2 ;
Query OK, 0 rows affected (0.00 sec)
mysql> show procedure status;
+------+---------+-----------+----------------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+
| Db | Name | Type | Definer | Modified | Created | Security_type | Comment | character_set_client | collation_connection | Database Collation |
+------+---------+-----------+----------------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+
| test | p_test1 | PROCEDURE | [email protected] | 2018-09-12 17:44:40 | 2018-09-12 17:44:40 | DEFINER | | utf8 | utf8_general_ci | utf8_general_ci |
+------+---------+-----------+----------------+---------------------+---------------------+---------------+---------+----------------------+----------------------+--------------------+
1 row in set (0.00 sec)
查看存储过程的创建代码
mysql> show create procedure p_test1\G
*************************** 1. row ***************************
Procedure: p_test1
sql_mode: STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION
Create Procedure: CREATE DEFINER=`root`@`localhost` PROCEDURE `p_test1`()
BEGIN
INSERT INTO test_event(username,password,create_time) values(‘tomcat‘, ‘xiaohuahua‘,now());
END
character_set_client: utf8
collation_connection: utf8_general_ci
Database Collation: utf8_general_ci
1 row in set (0.00 sec)
mysql>
解释:
默认情况下,存储过程和默认的数据库相关联,如果先想指定存储过程创建在某个特定的数据库下,那么在过程前面加数据库名做前缀;
在定义过程时,使用DELIMITER // 命令将语句的结束符号从分号 ; 临时改为两个//,使得过程体中使用的分号被直接传递到服务器,而不会被客户端(如mysql)解释。
3.2调用存储过程:call sp_name[(传参)];
实例三:创建一个MySQL定时器调用实例二创建的MySQL存储过程p_test1
提示mysql定时器的创建可以参考此博文:
从2018-09-12 17点47分开始每60秒执行一次
DELIMITER //
CREATE EVENT e_test1
ON SCHEDULE EVERY 60 second STARTS TIMESTAMP ‘2018-09-12 17:47:00‘
ON COMPLETION PRESERVE
DO
BEGIN
CALL p_test1();
END//
delimiter ;
mysql> select * from test_event;
+----+----------+------------+---------------------+
| id | username | password | create_time |
+----+----------+------------+---------------------+
| 1 | tomcat | xiaohuahua | 2018-09-12 17:18:01 |
| 2 | tomcat | xiaohuahua | 2018-09-12 17:18:39 |
| 3 | tomcat | xiaohuahua | 2018-09-12 17:18:45 |
| 0 | tomcat | xiaohuahua | 2018-09-12 17:47:00 |
| 0 | tomcat | xiaohuahua | 2018-09-12 17:48:00 |
| 0 | tomcat | xiaohuahua | 2018-09-12 17:49:00 |
| 0 | tomcat | xiaohuahua | 2018-09-12 17:50:00 |
| 0 | tomcat | xiaohuahua | 2018-09-12 17:51:00 |
+----+----------+------------+---------------------+
21 rows in set (0.00 sec)
说明:
在创建的存储过程中设置了需要传参的变量时,调用存储过程的时候,通过传参将数值赋值给存储工程中设置的变量,然后进行存储过程里的SQL操作。
3.3存储过程体
存储过程体包含了在过程调用时必须执行的语句,例如:dml、ddl语句,if-then-else和while-do语句、声明变量的declare语句等
过程体格式:以begin开始,以end结束(可嵌套)
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BEGIN
BEGIN
BEGIN
statements;
END
END
END
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注意:每个嵌套块及其中的每条语句,必须以分号结束,表示过程体结束的begin-end块(又叫做复合语句compound statement),则不需要分号。
4、为语句块贴标签
[begin_label:] BEGIN
[statement_list]
END [end_label]
例如:
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label1: BEGIN
label2: BEGIN
label3: BEGIN
statements;
END label3 ;
END label2;
END label1
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标签有两个作用:
①增强代码的可读性
②在某些语句(例如:leave和iterate语句),需要用到标签
原文地址:http://blog.51cto.com/wujianwei/2174878