--有输入参数的存储过程--
create proc GetComment
(@commentid int)
as
select * from Comment where CommentID=@commentid
 
--有输入与输出参数的存储过程--
create proc GetCommentCount
@newsid int,
@count int output
as
select @count=count(*) from Comment where NewsID=@newsid
 
 
--返回单个值的函数--
create function MyFunction
(@newsid int)
returns int
as
begin
declare @count int
select @count=count(*) from Comment where NewsID=@newsid
return @count
end
 
--调用方法--
declare @count int
exec @count=MyFunction 2
print @count
 
--返回值为表的函数--
Create function GetFunctionTable
(@newsid int)
returns table
as
return
(select * from Comment where NewsID=@newsid)
 
--返回值为表的函数的调用--
select * from GetFunctionTable(2)

--以前拼接的写法
　　set @sql=' select * from table where 1=1 '
　　if (@addDate is not null)
　　 set @sql = @sql+' and addDate = '+ @addDate + ' '
　　if (@name <>'' and is not null)
　　 set @sql = @sql+ ' and name = ' + @name + ' '
　　exec(@sql)

　　--第一种写法是 感觉代码有些冗余
　　if (@addDate is not null) and (@name <> '')
　　 select * from table where addDate = @addDate and name = @name
　　else if (@addDate is not null) and (@name ='')
　　 select * from table where addDate = @addDate
　　else if(@addDate is null) and (@name <> '')
　　 select * from table where and name = @name
　　else if(@addDate is null) and (@name = '')
　　select * from table
　　--第二种写法是
　　select * from table where (addDate = @addDate or @addDate is null) and (name = @name or @name = '')
　　--第三种写法是
　　SELECT * FROM table where
　　addDate = CASE @addDate IS NULL THEN addDate ELSE @addDate END,
　　name = CASE @name WHEN '' THEN name ELSE @name END

--简单赋值
declare @a int
set @a=5
print @a
 
--使用select语句赋值
declare @user1 nvarchar(50)
select @user1= '张三'
print @user1
declare @user2 nvarchar(50)
select @user2 = Name from ST_User where ID=1
print @user2
 
--使用update语句赋值
declare @user3 nvarchar(50)
update ST_User set @user3 = Name where ID=1
print @user3
 

--创建临时表1
create table #DU_User1
(
   [ID] [ int ]  NOT NULL ,
   [Oid] [ int ] NOT NULL ,
   [Login] [nvarchar](50) NOT NULL ,
   [Rtx] [nvarchar](4) NOT NULL ,
   [ Name ] [nvarchar](5) NOT NULL ,
   [ Password ] [nvarchar]( max ) NULL ,
   [State] [nvarchar](8) NOT NULL
);
--向临时表1插入一条记录
insert into #DU_User1 (ID,Oid,[Login],Rtx, Name ,[ Password ],State) values (100,2, 'LS' , '0000' , '临时' , '321' , '特殊' );
 
--从ST_User查询数据，填充至新生成的临时表
select * into #DU_User2 from ST_User where ID<8
 
--查询并联合两临时表
select * from #DU_User2 where ID<3 union select * from #DU_User1
 
--删除两临时表
drop table #DU_User1
drop table #DU_User2
 
--创建临时表
CREATE TABLE #t
(
   [ID] [ int ] NOT NULL ,
   [Oid] [ int ] NOT NULL ,
   [Login] [nvarchar](50) NOT NULL ,
   [Rtx] [nvarchar](4) NOT NULL ,
   [ Name ] [nvarchar](5) NOT NULL ,
   [ Password ] [nvarchar]( max ) NULL ,
   [State] [nvarchar](8) NOT NULL ,
)
 
--将查询结果集（多条数据）插入临时表
insert into #t select * from ST_User
--不能这样插入
--select * into #t from dbo.ST_User
 
--添加一列，为int型自增长子段
alter table #t add [myid] int NOT NULL IDENTITY(1,1)
--添加一列，默认填充全球唯一标识
alter table #t add [myid1] uniqueidentifier NOT NULL default (newid())
 
select * from #t
drop table #t
--给查询结果集增加自增长列
 
--无主键时：
select IDENTITY( int ,1,1) as ID, Name ,[Login],[ Password ] into #t from ST_User
select * from #t
 
--有主键时：
select ( select SUM (1) from ST_User where ID<= a.ID) as myID,* from ST_User a order by myID
--定义表变量
declare @t table
(
   id int not null ,
   msg nvarchar(50) null
)
insert into @t values (1, '1' )
insert into @t values (2, '2' )
select * from @t

--while循环计算1到100的和
declare @a int
declare @ sum int
set @a=1
set @ sum =0
while @a<=100
begin
   set @ sum +=@a
   set @a+=1
end
print @ sum

--if,else条件分支
if(1+1=2)
begin
   print '对'
end
else
begin
   print '错'
end
 
--when then条件分支
declare @today int
declare @week nvarchar(3)
set @today=3
set @week= case
   when @today=1 then '星期一'
   when @today=2 then '星期二'
   when @today=3 then '星期三'
   when @today=4 then '星期四'
   when @today=5 then '星期五'
   when @today=6 then '星期六'
   when @today=7 then '星期日'
   else '值错误'
end
print @week
 

declare @ID int
declare @Oid int
declare @Login varchar (50)
 
--定义一个游标
declare user_cur cursor for select ID,Oid,[Login] from ST_User
--打开游标
open user_cur
while @@fetch_status=0
begin
--读取游标
   fetch next from user_cur into @ID,@Oid,@Login
   print @ID
   --print @Login
end
close user_cur
--摧毁游标
deallocate user_cur

declare @ID int
declare @Oid int
declare @Login varchar (50)
 
--定义一个游标
declare user_cur cursor for select ID,Oid,[Login] from ST_User
--打开游标
open user_cur
while @@fetch_status=0
begin
--读取游标
   fetch next from user_cur into @ID,@Oid,@Login
   print @ID
   --print @Login
end
close user_cur
--摧毁游标
deallocate user_cur

--创建触发器
Create trigger User_OnUpdate 
   On ST_User 
   for Update 
As 
   declare @msg nvarchar(50)
   --@msg记录修改情况
   select @msg = N '姓名从“' + Deleted. Name + N '”修改为“' + Inserted. Name + '”' from Inserted,Deleted
   --插入日志表
   insert into [LOG](MSG) values (@msg)
   
--删除触发器
drop trigger User_OnUpdate

--创建带output参数的存储过程
CREATE PROCEDURE PR_Sum
   @a int ,
   @b int ,
   @ sum int output
AS
BEGIN
   set @ sum =@a+@b
END
 
--创建Return返回值存储过程
CREATE PROCEDURE PR_Sum2
   @a int ,
   @b int
AS
BEGIN
   Return @a+@b
END
   
--执行存储过程获取output型返回值
declare @mysum int
execute PR_Sum 1,2,@mysum output
print @mysum
 
--执行存储过程获取Return型返回值
declare @mysum2 int
execute @mysum2= PR_Sum2 1,2
print @mysum2

--新建标量值函数
create function FUNC_Sum1
(
   @a int ,
   @b int
)
returns int
as
begin
   return @a+@b
end
 
--新建内联表值函数
create function FUNC_UserTab_1
(
   @myId int
)
returns table
as
return ( select * from ST_User where ID<@myId)
 
--新建多语句表值函数
create function FUNC_UserTab_2
(
   @myId int
)
returns @t table
(
   [ID] [ int ] NOT NULL ,
   [Oid] [ int ] NOT NULL ,
   [Login] [nvarchar](50) NOT NULL ,
   [Rtx] [nvarchar](4) NOT NULL ,
   [ Name ] [nvarchar](5) NOT NULL ,
   [ Password ] [nvarchar]( max ) NULL ,
   [State] [nvarchar](8) NOT NULL
)
as
begin
   insert into @t select * from ST_User where ID<@myId
   return
end
 
--调用表值函数
select * from dbo.FUNC_UserTab_1(15)
--调用标量值函数
declare @s int
set @s=dbo.FUNC_Sum1(100,50)
print @s
 
--删除标量值函数
drop function FUNC_Sum1