sql进阶

--1.变量的声明和赋值

 

declare @Start DateTime,

@End DateTime

set @Start = '1999-9-9'

set @End = '2000-1-1'

 

select @Start,@End

 

--2.表变量

 

declare @tb1 table

(

ID int,

Name varchar(20),

Age int

)

insert into @tb1 values(1,'小明',7);

insert into @tb1 values(2,'小红',8);

select * from @tb1

 

--3.临时表--创建

 

if OBJECT_ID('tempdb..#tmp1') is not null drop table #tmp1

Create table #tmp1

(

ID int,

Name varchar(20)

)

insert into #tmp1 values(1,'Ami')

insert into #tmp1 values(2,'DaMing')

select * from #tmp1

 

--4.临时表--select into

 

if OBJECT_ID('tempdb..#tmp2') is not null drop table #tmp2

select * into #tmp2

from

(

select * from @tb1

) as tmp

select * from #tmp2

 

--5.isnull()函数

 

select isnull(null,0)

 

 

--6.if else

 

if(@Start > '2008-1-1')

begin

select '大于'

end

else select '小于'

 

--7.case xxx when

 

declare @sex int

set @sex =1

select

case @sex

when 1 Then '男'

when 0 Then '女'

end

 

--8.case when

 

select

case @sex

when 1 then '男'

when 0 then '女'

end

 

--9.union all 和 left join

 

--left join 还是比较熟悉的，是左连接，一个表从右边过来接上左边的表。

--union all 就算是【向下连接】了

select '小明'

union all

select '小红'

union all

select '小刚'

 

--10.调用另一个存储过程

 

--exec sp_StorageSum @Start,@End,'全部'