use test;drop table if exists t8;CREATE TABLE t8(s1 INT,PRIMARY KEY(s1));drop procedure if exists handlerdemo;DELIMITER $$CREATE PROCEDURE handlerdemo()BEGINdeclare xx int default 4;DECLARE oh_no condition for sqlstate '23000';#DECLARE CONTINUE HANDLER FOR SQLSTATE '23000' SET @X2=1;declare exit handler for oh_no set @info='违反主键约束';SET @X=1;INSERT INTO t8 VALUES(1);SET @X=2;INSERT INTO t8 VALUES(1);SET @X=3;END
调用存储过程
/* 调用存储过程*/CALL handlerdemo();/* 查看调用存储过程结果*/SELECT @X,@info;
心得体会:
1、语句结束符
也许mysql是将存储过程、自定义函数看作一条语句的,因此,存储过程里多条语句用“;”隔开,为了避免冲突,就要用delimiter 重新定义结束符。
一般可以在存储过程开始前,定义新的结束符,如
delimiter //
存储过程书写完毕以后,再恢复定义:delimiter ;
但也可以在存储过程开始前,这样写 delimiter $$,但存储过程后不可以再写别的语句了。如上面的例子
2、变量
mysql的变量,跟SQL SERVER一样,形如 @X ,但无需声明,直接使用。
而在存储过程里面,变量无须用 @,但要声明。并且声明要放在存储过程的头部(?),如本例,否则报错。真奇怪啊,一方面,有时候变量无须声明就可以使用,另一方面,有时候又要限定声明位置,令人无所适从,似乎随便了点。
存储过程内部的变量,作用范围仅限于存储过程。但那些带@的变量,却仿佛可以跨越会话和连接,看上去是全局变量?如上面的例子。
3、条件和处理
定义条件,是为了给处理调用。如上面的例子:
DECLARE oh_no condition for sqlstate '23000';#DECLARE CONTINUE HANDLER FOR SQLSTATE '23000' SET @X2=1;declare exit handler for oh_no set @info='违反主键约束';

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