sql server常用知识点

--删除表

use [20130823_Recource]

go

drop table my_table1,my_table2,My_table3

--创建表

use [20130823_Recource]

go

if(exists(select * from sys.objects where name='Student1'))

drop table Student1

go

create table Student1

(

Id int primary key identity(1,2) not null,

Name nvarchar(30) not null,

Age int not null,

MyMoney decimal ,

CreateDateTime datetime default getdate()

)

--插入数据

insert into Student values('zhangsan',34,2300,GETDATE())

insert into Student

select 'zhangsi',23,4300 ,GETDATE()union

select 'zhangwu',33,5400,GETDATE() union

select 'zhanghong',12,2300,GETDATE()

--修改数据

update Student set MyMoney=10000 where Age=12

--删除数据

delete Student  where Age=12

truncate table student

--存储过程

if(exists(select * from sys.objects where name='proc_Name'))

drop proc proc_Name

go

create proc proc_Name(@number int,@number1 int output)

as

begin

select @number1=su.MyMoney from Student as su where su.Id=@number

end

--执行存储过程

declare @num int

exec proc_Name 3,@num output

print @num

--统计存储过程写法

create procedure proc_name

@CountDate datetime=null --统计时间

as

begin

　　if(@CountDate is null)　　--统计时间为空则赋值

　　begin

　　　　set @CountDate=dateadd(day,-1,getdate());

     end

　　if exists(select top 1* from 表 where datediff(day,Countdate,@Countdate)=0) --如果统计过了则退出

　　return;

end

--函数

if(exists(select * from sys.objects where name='function_Name'))

drop function function_Name

go

create function function_Name(@number int)

returns int

as

begin

declare @number1 int

select @number1=su.MyMoney from Student as su where su.Id=@number

return @number1

end

--执行函数

select dbo.function_Name(3)

--视图

if(exists(select * from sys.objects where name='view_Name'))

drop view view_Name

go

create view view_Name

as

select * from Student where ID=3

--执行函数

select * from view_Name

--游标

declare cursor_name cursor scroll for

select su.Name from student as su

open cursor_name

declare @Name nvarchar(20)

fetch last from cursor_name into @Name

print @Name

fetch absolute 3 from cursor_name into @Name

print @Name

fetch relative 1 from cursor_name into @Name

print @Name

fetch prior from cursor_name into @Name

print @Name

fetch first from cursor_name into @Name

while(@@FETCH_STATUS=0)

begin

print @Name

fetch next from cursor_name into @Name

end

close cursor_name

deallocate cursor_name

--事务

begin tran tran_Name

declare @error int

set @error=0

begin try

update Student set MyMoney=MyMoney+1000 where ID=1

set @error=@error+@@ERROR;

update Student set MyMoney =MyMoney -1000 where ID=2

set @error=@error +@@ERROR;

end try

begin catch

print '错误号：'+error_number()+'错误信息:'+error_message()

set @error=@error+1;

end catch

if(@error>=1)

begin

rollback tran

print '失败'

end

else

begin

commit tran

print '成功'

end

--触发器

if(exists(select * from sys.objects where name='trigger_Name'))

drop trigger trigger_Name

go

create trigger trigger_Name

on student

for delete

as

insert into Student values('zhangsss',11,3400,GETDATE())

--执行触发器

delete Student where ID=1

--排名

select *,ROW_NUMBER() over(partition by name order by id) as ran from Student

select *,RANK() over(order by id) as ran from Student

select *,DENSE_RANK() over(order by id ) as ran from Student

select *,NTILE(2) over(order by id) as ran from Student

--开窗函数

Count（*）

--集合

select * from Student

union--合并

select * from Student1

select * from Student

intersect--交集

select * from Student1

select * from Student

except--除去

select * from Student1

--连接

select su.name,su1.Name from Student as su

inner join Student1 as su1

on su.id=su1.Id

select su.name,su1.Name from Student as su

left join Student1 as su1

on su.id=su1.Id

select su.name,su1.Name from Student as su

right join Student1 as su1

on su.id=su1.Id

--case

select *,case

when MyMoney<=2500 then '穷人'

when 2500<MyMoney and MyMoney<=4500 then '资产'

when 4500<MyMoney then '富人'

end as ran

from Student1

--while循环

while(@number>0)

begin

end

--常用函数

select distinct top 2 * from Student --top,distinct

select isnull(null,2) --判断是否为null

select getdate() --获得日期

select datename(DAY,GETDATE())--获得日期的某一字段

select dateadd(MONTH,1,GETDATE()) --当前日期加

select COUNT(*),AVG(su.MyMoney),SUM(su.MyMoney),MIN(su.MyMoney),MAX(su.MyMoney) from Student as su --系统函数

select * from Student su where su.Id<>5 -- 符合：<、>、<>、<=、=>

select * from Student su where su.Name like'%wu'--模糊查询:%、_、[]、^

select * from Student su where su.Id between 2 and 6 -- between and

select * from Student su where su.Id in(3,4,5)--in()

select Age from Student su group by su.Age having Age>22 --筛选分组

select * from Student su order by su.Id desc--排序

select isnull(a.id,0)--为空就为0

触发器的两个重要的表

对表的操作	Inserted逻辑表	Deleted逻辑表
增加记录（insert）	存放增加的记录	无
删除记录（delete）	无	存放被删除的记录
修改记录（update）	存放更新后的记录	存放更新前的记录

触发器回滚

if(exists(select * from sys.objects where name = 'tr_Valid'))

drop trigger tr_Valid

go

create trigger tr_Valid

on mymsg

for insert

as

declare @age int;

select @age=age from inserted

if(@age>50)

begin

insert into mymsg select Name,Age from inserted

end

else

begin

print 'age数值不正确'

rollback tran;--数据不正确，就执行回滚业务

end

insert into mymsg values('zl68',51) --测试

读取相关文章数据

Select top 10 * from stu order by newid()--获得随机10条

Select top 1 * from stu where id>@0 order by id asc--下一条//@0为传入参数

Select top 1 * from stu where id<@0 order by id desc--上一条//@0为传入参数

--日期处理

DATEADD(s,CreatedAt,'1970-1-1 08:00:00') --秒转换成日期

convert(smalldatetime,convert(varchar(10),getdate(),120))--字符串转换为日期

dateadd(mm,datediff(mm,0,'2015-02-11'),0)--月第一天

dateadd(ms,-3,dateadd(mm,datediff(m,0,'2015-02-11')+1,0))--月最后一天

dateadd(mm,datediff(mm,0,'2015-02-11')+1,0)--下个月第一天

dateadd(mm,datediff(mm,0,'2015-02-11')+2,-1)--下个月最后一天

dateadd(yy,datediff(yy,0,getdate()),0)--一年中第一天

dateadd(day,7,dateadd(day,2-(case when datepart(weekday,'2015-02-11')=1 then 8 else datepart(weekday,'2015-02-11') end),'2015-02-11'))--周一

dateadd(day,7,dateadd(day,8-(case when datepart(weekday,'2015-02-11')=1 then 8 else datepart(weekday,'2015-02-11') end),'2015-02-11'))--周日

字符串截取

case when Len(UserDesc)>3 then substring(UserDesc,0,3)+'...'

when Len(UserDesc)<=3 then UserDesc

end as UserDesc