Mysql事項,視圖,函數(shù),觸發(fā)器命令(詳解)

//修改表的引擎
alter table a engine=myisam;
//開啟事務
begin;
//關(guān)閉自動提交
set autocommit=0;
//扣100
update bank set money=money-100 where bid=1;
//回滾，begin開始的所有sql語句操作
rollback;

//開啟事務
begin;
//關(guān)閉自動提交
set autocommit=0;
//扣100
update bank set money=money-100 where bid=1;
//加100
update bank set money=money+100 where bid=2;
//提交
commit;

$dsn = "mysql:host=127.0.0.1;dbname=c58";
try {
  //通過pdo連接數(shù)據(jù)庫
  $pdo = new Pdo($dsn,'root','');
  //把錯誤設(shè)置成異常模式，才能try catch接收
  $pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
  //設(shè)置字符集
  $pdo->query("SET NAMES utf8");
  //開啟事務
  $pdo->query("BEGIN");
  //關(guān)閉自動提交
  $pdo->query("SET AUTOCOMMIT=0");
  //轉(zhuǎn)賬
  //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();
}

//1.創(chuàng)建視圖
create view bankview as select bid,bname from bank;
//2.查看視圖
show table status where comment='VIEW';
//3.修改視圖
alter view bankview as select bid from bank;
//4.刪除視圖
drop view bankview;

//更變邊界符
\d $

//創(chuàng)建存儲過程
create procedure get_bid(inout n char(20) charset utf8)
begin
  select bid from bank where name=n;
end
$

//調(diào)用
set @name='震'$
call get_bid(@name)$

//存儲過程作業(yè)
//1. 創(chuàng)建刪除班級的存儲過程
//2. 實現(xiàn)刪除班級時一并刪除此班級中的學生
//3. 調(diào)用方式call del_class(1);
//創(chuàng)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(輸出外面?zhèn)魅氲闹担荒芨淖兺饷鎮(zhèn)魅氲闹?
create procedure a(in id int)
begin
  select id;
  set id=100;
end
$

//2.out(不可以輸出外面?zhèn)魅氲闹?，能改變外面?zhèn)魅氲闹?
create procedure b(out id int)
begin
  select id;
  set id=100;
end
$

//3.inout（綜合上述兩種情況）
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
$

//查看狀態(tài)
show procedure status;

//刪除get_bid這個存儲過程
drop procedure get_bid;

//創(chuàng)建
create function hello(s char(20) charset utf8)
returns char(50)
reads sql data
begin
  return concat('hello ',s,' !');
end
$

//調(diào)用
select hello('hdw')$
+--------------+
| hello('hdw') |
+--------------+
| hello hdw ! |
+--------------+

//刪除
drop function hello$

//創(chuàng)建存儲函數(shù)
create function getcid(n char(20) charset utf8)
returns int
reads sql data
begin
  return (select cid from stu where sname=n);
end
$
//存儲函數(shù)可以用在sql語句中
select cname from class where cid=getcid('小貓')$

//刪除班級自動觸發(fā)刪除學生
create trigger del_class_stu after delete on class
for each row
begin
  delete from stu where cid=old.cid;
end
$

//觸發(fā)器作業(yè)
創(chuàng)建文章表含標題、作者、發(fā)布時間字段
如果只添加了標題,發(fā)布時間字段自動設(shè)置為當前時間,
作者字段設(shè)置為123網(wǎng)
\d $
create trigger this_name before insert on this_table for each row
begin
if new.uname is null then
set new.uname='123';
end if;
if new.timer is null then
set new.timer=unix_timestamp(now());
end if;
end
$

//查詢已有觸發(fā)器
show triggers;