declare @变量名 类型set @变量名=值eg、--查汽车表中名称含有宝马两个字的
declare @name varchar(20)
set @name='宝马'
select * from car where Name like '%'+@name+'%'-- 查汽车表中所有汽车的平均值并输出
declare @price decimal(10,4)
select @price = AVG(Price) from Car
print '所有汽车的平均价格为：'+cast(@price as varchar(20))

1 if 判断条件
2 begin
3 　　要执行的语句
4 end
5 else
6 begin
7 　　要执行的语句
8 end

CASE sexWHEN '1' THEN '男'WHEN '2' THEN '女'ELSE'其他'END

CASEWHEN sex = '1' THEN '男'WHEN sex = '2' THEN '女'ELSE'其他'END

1 declare @ccname varchar(20)
2 set @ccname = '宝马'
3 select * from Car where Name like
4 case
5 　　when @ccname='宝马' then '%宝马%'
6 　　when @ccname='奥迪' then '%奥迪%'
7 else '%'
8 end

1 create procedure MyPRO --procedure为创建存储过程关键字，也可以简写proc，MyPRO为存储过程名
2 as
3 select * from authors
4 --执行存储过程
5 exec mypro  --exec表示执行存储过程

 1 create procedure BuyFriut
 2 @Uid varchar(50),
 3 @Fcode varchar(50),
 4 @Sl int
 5 as
 6 begin
 7     declare @kc int,@price float
 8     select @kc=Numbers,@price=Price from Fruit where Ids=@Fcode
 9     if @Sl>@kc
10     begin
11         print '库存不足！'
12     end
13     else
14     begin
15         declare @ye float
16         select @ye=Account from Login where UserName=@Uid
17         if @ye>= @price*@Sl
18         begin
19             update Fruit set Numbers=Numbers-@Sl where Ids=@Fcode
20             update Login set Account=Account-@price*@Sl where UserName=@Uid
21             declare @sj int
22             set @sj = cast(rand()*10000    as int)
23             insert into Orders values(@sj,@Uid,GETDATE())--添加内容的时候 先写主键表，再写外键表
24             insert into OrderDetails values(@sj,@Fcode,@Sl)
25         end
26         else
27         begin
28             print '余额不足！'
29
30         end
31     end
32 end
33
34 go
35 --使用存储过程
36 declare @s int
37 exec  @s = BuyFriut 'wangwu','k001',20
38 print @s
39
40 --删除存储过程
41 drop proc BuyFriut

1 create trigger [shema_name . ] trg_name
2 on { table | view }
3 [ with encryption ]
4 { for | after | instead of }
5 { insert , update , delete }
6 as
7 sql_statement

 1 if(object_id('tgr_test_insert','tr') is not null)
 2     drop trigger tgr_test_insert --删除触发器
 3 go
 4 create trigger tgr_test_insert
 5 on student --创建在student表
 6     for insert --insert触发
 7 as
 8 declare @id int,@name varchar(20),@sex char(2),@age int
 9 --查询inserted表中已经插入的信息
10 select @id = id,@name = name,@sex = sex, @age = age from inserted
11 --用查到的信息加入到会员表中
12 if(@age >30) --如果年龄不符合 则修改
13 begin
14     update student set age = 30 where id = @id
15     print '年龄太大，已自动修改为30'
16 end
17 insert into [user] (userName,passWord,RoleId) values (@name,@sex + cast(@age as varchar),3)
18 print '添加学生成功！';
19 print '添加会员成功！'

insert into student (name,sex,age,mail) values ('海盗船长','男',88,'853020304@qq.com')

 1 if(object_id('tgr_student_update','tr') is not null)
 2     drop trigger tgr_student_update
 3 go
 4 create trigger tgr_student_update
 5 on student
 6     for update
 7 as
 8     declare @oldName varchar(10),@newName varchar(10)
 9     select @oldName = name from deleted; --查找更新前的数据
10     select @newName = name from inserted;--查找更新后的数据
11     if(@oldName = @newName)
12     begin
13         print '数据相同'
14         rollback tran;   --回滚 不执行修改操作
15     end
16     else
17         print '修改成功'

update student set name='海盗船长' 

update student set name='粉红娘娘'

 1 create trigger TR_STUDENT_DELETE
 2 on Student
 3 as
 4 begin
 5     declare @uid varchar(50),@name varchar(50)
 6     select @uid=UserName,@name=Name from deleted
 7     insert into biandong values(@uid,@name,'删除')
 8 end
 9
10  go
11   --在对表loginnoe进行删除的时候触发器执行
12  delete from Loginone where UserName='aaa'
13
14  go

if(object_id('tgr_student_delete','tr')is not null)drop trigger tgr_student_delete
go
create trigger tgr_student_delete
on studentfor delete
asif(exists(select * from sys.databases where name = 'studentBackup'))insert into studentBackup select name,sex,age,mail from deleted;elseprint '不存在，创建再插入'create table studentBackup(name varchar(20),sex char(2),age int,mail varchar(20))insert into studentBackup select name,sex,age,mail from deleted;

delete from studentselect * from student
select * from studentBackup

 1  --删除student里面的数据的时候用另外两条语句替代，先删从表再删主表
 2
 3 create trigger TR_STUDENT_DELETE
 4  on Student
 5  instead of delete
 6 as
 7 begin
 8      declare @sno varchar(20)
 9      select @sno=sno from deleted
10      delete from score where sno=@sno
11      delete from student where sno=@sno
12 end
13  --执行删除的时候触发
14  delete from student

if(object_id('tgr_student_inteadof','tr') is not null)drop trigger tgr_student_inteadof
go
create trigger tgr_student_inteadof
on studentinstead of delete -- update , insert
asdeclare @id int,@name varchar(20)select @id = id,@name = name from deleted;--instead of 先触发--先删除user表信息delete from [user] where userName = @name;--再删除student表信息delete from [student] where id = @id;delete from student where name = '海盗船长'

alter trigger tgr_test_insert
on student
for insert
as
print 'ok'

disable trigger tgr_test_insert on student

enable trigger tgr_test_insert on student

select * from sys.triggers

 select * from Carselect * from Brandbegin transaction --开始事务delete from Car where Code='c005'delete from Brand where Brand_Code='b002'if @@ERROR=0--判断是否出错,如果执行没错@@ERROR为0
begincommit -- 提交事务
endelsebeginrollback--回滚事务
end--try catchbegin transaction --开始事务begin try --try里面写要执行的代码delete from Car where Code='c005'delete from Brand where Brand_Code='b002'commitend trybegin catchrollbackend catch