MySql学习心得之存储过程
编程学习 2021-07-05 15:27www.dzhlxh.cn编程入门
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：
代码如下:
#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：
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。
代码如下:
#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：
代码如下:
UPDATE gk_permission SET `level` = @plevel, power = @ppower WHERE user_uid = CONVERT(@puser_uid USING utf8) COLLATE utf8_unicode_ci;
代码如下:
#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 ;
代码如下:
#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 ;
代码如下:
#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）。
代码如下:
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。