Mysql事项,视图,函数,触发器命令(详解)

事项开启和使用

//修改表的引擎alter table a engine=myisam;//开启事务begin;//关闭自动提交set autocommit=0;//扣100update bank set money=money-100 where bid=1;//回滚，begin开始的所有sql语句操作rollback;//开启事务begin;//关闭自动提交set autocommit=0;//扣100update bank set money=money-100 where bid=1;//加100update bank set money=money+100 where bid=2;//提交commit;

实例操作

$dsn = "mysql/' target='_blank'>mysql:host=127.0.0.1;dbname=c58";try {  //通过pdo连接数据库  $pdo = new Pdo($dsn,'root','');  //把错误设置成异常模式，才能try catch接收  $pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);  //设置字符集  $pdo->query("SET NAMES utf8");  //开启事务  $pdo->query("BEGIN");  //关闭自动提交  $pdo->query("SET AUTOCOMMIT=0");  //转账  //扣掉100  $pdo->exec('UPDATE bank SET money=money-100 WHERE bid=1');  //加上100  $pdo->exec('UPDATE bank SET money=money+100 WHERE bid=2');  //提交  $pdo->query('COMMIT');} catch (PDOException $e) {  $pdo->query('ROLLBACK');  echo $e->getMessage();}

注释：事项可以帮助我们更安全的操作数据

视图的创建删除和使用

//1.创建视图create view bankview as select bid,bname from bank;//2.查看视图show table status where comment='VIEW';//3.修改视图alter view bankview as select bid from bank;//4.删除视图drop view bankview;

存储过程的创建删除查询和使用

//更变边界符

//更变边界符\d $//创建存储过程create procedure get_bid(inout n char(20) charset utf8)begin  select bid from bank where name=n;end$//调用set @name='震'$call get_bid(@name)$//存储过程作业//1. 创建删除班级的存储过程//2. 实现删除班级时一并删除此班级中的学生//3. 调用方式call del_class(1);//创建表create table class(  cid int unsigned primary key auto_increment,  cname char(20) not null default '');create table stu(  sid int unsigned primary key auto_increment,  sname char(20) not null default '',  cid int unsigned not null default 0);\d $create procedure del_class(inout id smallint)begin  delete from class where cid=id;  delete from stu where cid=id;end$set @id=1$call del_class(@id)$//1.in(输出外面传入的值，不能改变外面传入的值)create procedure a(in id int)begin  select id;  set id=100;end$//2.out(不可以输出外面传入的值，能改变外面传入的值)create procedure b(out id int)begin  select id;  set id=100;end$//3.inout（综合上述两种情况）create procedure insert_data(in num int)begin  while num > 0 do  insert into class set cname=num;  set num = num - 1;  end while;end$//查看状态show procedure status;//删除get_bid这个存储过程drop procedure get_bid;

存储函数创建删除和使用

//创建create function hello(s char(20) charset utf8)returns char(50)reads sql databegin  return concat('hello ',s,' !');end$//调用select hello('hdw')$+--------------+| hello('hdw') |+--------------+| hello hdw ! |+--------------+//删除drop function hello$//创建存储函数create function getcid(n char(20) charset utf8)returns intreads sql databegin  return (select cid from stu where sname=n);end$//存储函数可以用在sql语句中select cname from class where cid=getcid('小猫')$

触发器创建删除和使用

//删除班级自动触发删除学生create trigger del_class_stu after delete on classfor each rowbegin  delete from stu where cid=old.cid;end$//触发器作业创建文章表含标题、作者、发布时间字段如果只添加了标题,发布时间字段自动设置为当前时间,作者字段设置为123网\d $create trigger this_name before insert on this_table for each rowbeginif new.uname is null thenset new.uname='123';end if;if new.timer is null thenset new.timer=unix_timestamp(now());end if;end$//查询已有触发器show triggers;

注释：触发器是设置好当执行某一个行为时执行另一个方法！

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