一个简单的外键加事务mysql代码
mysql

什么叫外键:保持表中数据的一致性,完整性。使两张表可以极联更新,和极联删除。 具体分化为:RESTRICT,NO ACTION,CASCADE ,SET NULL 事务:主要用于同步数据的同步性,防止由于忽发状况,数据之间出现断层。
drop database if exists nosay1; create database nosay1 character set utf8; use nosay1; create table usertable (id int primary key auto_increment,username varchar(10) not null default 'nodefine',password varchar(36) not null default '12345')character set utf8 engine innodb; create table userinfo(id int primary key auto_increment,`money` decimal(8) not null default '0',usertable_id int ,foreign key (usertable_id) references usertable(id) on delete cascade on update cascade )character set utf8 engine innodb; create table `class`(id int primary key auto_increment,`money` decimal(8) not null default '0',`count` tinyint(4) not null default '0')character set utf8 engine innodb; start transaction; insert into `class` values ('','',''); commit; delimiter $$ create trigger insert_usertable after insert on usertable for each row begin insert into userinfo values (null,'2000',new.id); update userinfo set `money` = `money`-200 where usertable_id=new.id; update `class` set `money` = `money`+200,`count` = `count`+1; end delimiter ; delimiter $$ create trigger delete_usertable after delete on usertable for each row begin update `class` set `money` = `money`-200,`count` = `count`-1; end delimiter ; insert into usertable values (null,'nosay','12345');