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MySql学习心得之存储过程

之前总是在MSSQL上写存储过程,没有在MYSQL上写过,也基本没有用过,今天需要用到MYSQL,研究了下,把项目的需要的存储过程写了一部分,写一下工作总结。这里没有给出数据库结构,不讨论SQL语句的细节,主要探讨存储过程语法,适合有基础的人。

先来看段mysql查询文章回复语句:

#查询文章回复
-- ----------------------------
-- Procedure structure for `sp_select_reply_article`
-- ----------------------------
DROP PROCEDURE IF EXISTS `sp_select_reply_article`;
DELIMITER ;;
CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_select_reply_article`(IN `ra_id` int,IN `pagefrom` int,IN `pagesize` int)
BEGIN
 #Routine body goes here...
 SET @ra_id = ra_id;
 SET @pagefrom = pagefrom;
 SET @pagesize = pagesize;
 SET @ssra = CONCAT('SELECT * FROM gk_article WHERE id = ? LIMIT ?,?');
 PREPARE sqlquery FROM @ssra;
 EXECUTE sqlquery USING @ra_id,@pagefrom,@pagesize;
END

DELIMITER ;

#技术点1:MySql5.1不支持LIMIT参数(MySql5.5就支持了),如果编写存储过程时使用LIMIT做变量,那是需要用动态SQL来构建的,而这样做性能肯定没有静态SQL好。主要代码如下:

 SET @ssra = CONCAT('SELECT * FROM gk_article WHERE id = ? LIMIT ?,?');
 PREPARE sqlquery FROM @ssra;
 EXECUTE sqlquery USING @ra_id,@pagefrom,@pagesize;
 
#技术点2:如果同时需要返回受影响行数需要在语句后面添加语句:ROW_COUNT()函数,两条语句之间需要“;”分隔。
#更新数据
-- ----------------------------
-- Procedure structure for `sp_update_permission`
-- ----------------------------
DROP PROCEDURE IF EXISTS `sp_update_permission`;
DELIMITER ;;
CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_update_permission`(IN `puser_uid` varchar(20),IN `plevel` int,IN `ppower` int)
BEGIN
 #Routine body goes here...

 SET @puser_uid = puser_uid;
 SET @plevel = plevel;
 SET @ppower = ppower;
 UPDATE gk_permission SET `level` = @plevel, power = @ppower WHERE user_uid = CONVERT(@puser_uid USING utf8) COLLATE utf8_unicode_ci;
END

DELIMITER ;

#技术点3:MySQL进行字符串比较时发生错误(Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='),解决方法:将比较等式一边进行字符串转换,如改为“CONVERT(b.fullCode USING utf8) COLLATE utf8_unicode_ci”,主要代码如下:

 UPDATE gk_permission SET `level` = @plevel, power = @ppower WHERE user_uid = CONVERT(@puser_uid USING utf8) COLLATE     utf8_unicode_ci;
 
#插入数据
-- ----------------------------
-- Procedure structure for `sp_insert_user`
-- ----------------------------
DROP PROCEDURE IF EXISTS `sp_insert_user`;
DELIMITER ;;
CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_insert_user`(IN `uid` varchar(20),IN `upw` varchar(32),IN `name` varchar(20),IN `sex` int,IN `phone` varchar(20),IN `u_id` int,IN `s_id` int,IN `j_id` int)
BEGIN
 #Routine body goes here...
 SET @uid = uid;
 SET @upw = upw;
 SET @uname = uname;
 SET @sex = sex;
 SET @phone = phone;
 #由于外键约束,所以添加的外键字段需要在对应外键所在表有相应数据
 SET @u_id = u_id;
 SET @s_id = s_id;
 SET @j_id = j_id;
 SET @verifytime = DATE('0000-00-00');
 INSERT INTO gk_user(uid,upw,uname,sex,phone,u_id,s_id,j_id,verifytime)
       VALUES(@uid,@upw,@uname,@sex,@phone,@u_id,@s_id,@j_id,@verifytime);
 #查询结果会自动返回受影响行数
END

DELIMITER ;
#根据ID删除数据
-- ----------------------------
-- Procedure structure for `sp_delete_exchange_by_id`
-- ----------------------------
DROP PROCEDURE IF EXISTS `sp_delete_exchange_by_id`;
DELIMITER ;;
CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_delete_exchange_by_id`(IN `eid` int)
BEGIN
 #Routine body goes here...
 SET @eid = eid;
 DELETE FROM gk_exchange WHERE id = @eid;
END

DELIMITER ;
#通过账号查询用户或者管理员
-- ----------------------------
-- Procedure structure for `sp_select_user_by_uid`
-- ----------------------------
DROP PROCEDURE IF EXISTS `sp_select_user_by_uid`;
DELIMITER ;;
CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_select_user_by_uid`(IN `uid` varchar(20),IN `getAdmin` int)
BEGIN
 #Routine body goes here...
 SET @uid = uid;
 #SET @getadmin = getAdmin;
 #查询管理员
 IF (getAdmin = 1) THEN
SELECT us.*, un.`name`, se.`name`, jo.`name`, pe.`level`, pe.power FROM gk_user AS us, gk_unit AS un, gk_section AS se, gk_jobtitle AS jo, gk_permission AS pe WHERE us.u_id = un.id AND us.s_id = se.id AND us.j_id = jo.id AND us.uid = pe.user_uid AND us.uid = CONVERT(@uid USING utf8) COLLATE utf8_unicode_ci;
 END IF;
 #查询用户
 IF (getAdmin = 0) THEN
SELECT us.*, un.`name`, se.`name`, jo.`name` FROM gk_user AS us, gk_unit AS un, gk_section AS se, gk_jobtitle AS jo WHERE us.u_id = un.id AND us.s_id = se.id AND us.j_id = jo.id AND us.uid = CONVERT(@uid USING utf8) COLLATE utf8_unicode_ci;
 END IF;
END

DELIMITER ;

#技术点4:这个存数过程需要用到控制语句(if else elseif while loop repeat leave iterate)。

 IF (getAdmin = 1) THEN
#语句…
 END IF;
 

#技术点5:在传入参数不匹配的情况下报错(Column count doesn't match value count at row 1),这个就是细心问题了,详细检查参数吧。

#技术点6:获取当前时间的函数:NOW()

#技术点7:“`”这个符号是反单引号,两个反单引号夹起来的会被当做变量,一般是在定义字段时遇到关键字冲突的时候会用到。



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