SQLServer 基本语法

--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

--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