SQL位运算

select 2|8       --10
select 2|8|1    --11

select 10&8    --8,包含,10=8+2
select 10&2    --2,包含,10=2+8
select 10&4    --0,不包含
select 19&16  --16,包含,19=16+2+1
select 19&8    --0,包含,19=16+2+1

select * from SqlBitOperation where FBitTags&4=4

在权限中的应用

1、两张表

（1）、操作与权限标志表

if exists (select * from sysobjects where id = OBJECT_ID('[RightTags]') and OBJECTPROPERTY(id, 'IsUserTable') = 1)
DROP TABLE [RightTags]

CREATE TABLE [RightTags] (
[Pkid] [int]  IDENTITY (1, 1)  NOT NULL,
[RightsName] [nvarchar]  (50) NOT NULL,
[RightsTag] [int]  NOT NULL DEFAULT (0))

ALTER TABLE [RightTags] WITH NOCHECK ADD  CONSTRAINT [PK_RightTags] PRIMARY KEY  NONCLUSTERED ( [Pkid] )

SET IDENTITY_INSERT [RightTags] ON
INSERT [RightTags] ([Pkid],[RightsName],[RightsTag]) VALUES ( 1,'吃饭',1)
INSERT [RightTags] ([Pkid],[RightsName],[RightsTag]) VALUES ( 2,'拉屎',2)
INSERT [RightTags] ([Pkid],[RightsName],[RightsTag]) VALUES ( 3,'打炮',4)
INSERT [RightTags] ([Pkid],[RightsName],[RightsTag]) VALUES ( 4,'泡妞',8)
INSERT [RightTags] ([Pkid],[RightsName],[RightsTag]) VALUES ( 5,'生子',16)
INSERT [RightTags] ([Pkid],[RightsName],[RightsTag]) VALUES ( 6,'包二奶',32)
SET IDENTITY_INSERT [RightTags] OFF

（2）、用户与权限表

if exists (select * from sysobjects where id = OBJECT_ID('[RightUsers]') and OBJECTPROPERTY(id, 'IsUserTable') = 1)
DROP TABLE [RightUsers]

CREATE TABLE [RightUsers] (
[Pkid] [int]  IDENTITY (1, 1)  NOT NULL,
[FUser] [nvarchar]  (50) NOT NULL,
[UserRights] [int]  NOT NULL DEFAULT (0))

ALTER TABLE [RightUsers] WITH NOCHECK ADD  CONSTRAINT [PK_RightUsers] PRIMARY KEY  NONCLUSTERED ( [Pkid] )

SET IDENTITY_INSERT [RightUsers] ON
INSERT [RightUsers] ([Pkid],[FUser],[UserRights]) VALUES ( 1,'张三',7)
INSERT [RightUsers] ([Pkid],[FUser],[UserRights]) VALUES ( 2,'李四',9)
INSERT [RightUsers] ([Pkid],[FUser],[UserRights]) VALUES ( 3,'王老板',63)
INSERT [RightUsers] ([Pkid],[FUser],[UserRights]) VALUES ( 4,'朱麻子',0)
SET IDENTITY_INSERT [RightUsers] OFF

2、访问判断是否有权限

--1.查询权限
declare @iRights as int
select @iRights=(select top 1 RightsTag from RightTags where RightsName='打炮')
--print @iRights
select * from RightUsers where UserRights&@iRights=@iRights --所有可以打炮的人
select * from RightUsers where FUser='李四' and UserRights&@iRights=@iRights   --此人是否可以打炮(有无记录集)
select * from RightUsers where FUser='王老板' and UserRights&@iRights=@iRights --此人是否可以打炮(有无记录集)

go

3、设置权限

--2.设置权限
declare @yourRights int
select @yourRights=(select sum(RightsTag) from RightTags where RightsName in('吃饭','拉屎','打炮'))
--print @yourRights

update RightUsers set UserRights=@yourRights where FUser='张三'
go

4、查看此人的所有权限

--3.查看此人的所有权限
declare @yourRights as int
select @yourRights=(select UserRights from RightUsers where FUser='李四')
print @yourRights

select * from RightTags where @yourRights&RightsTag=RightsTag
go

5、检测权限表权限值是否为2的整数次方(操作权限标志的有效性:唯一+2的整数次方)

select power(2,6) --64
select power(2.000,5.500) --45.255

select log(64.000)/log(2.000)--6.0

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declare @setNewOperateRightTags int --添加一个新操作权限
set @setNewOperateRightTags=64  --64是2的整数次方
--set @setNewOperateRightTags=63  --63不是2的整数次方

declare @number float
set @number=log(@setNewOperateRightTags)/log(2.000)
--print @number
if(ceiling(@number)=floor(@number))--取最大整数=取最小整数
begin
  print cast(@setNewOperateRightTags as varchar(16)) + '是2的整数次方,可以用作权限标志值'
end
else
begin
  print cast(@setNewOperateRightTags as varchar(16)) + '不是2的整数次方,不能用作权限标志值'
end
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