问题引入

这天老鸟火急火燎的跑到菜鸟旁边，想必是遇到什么难题了：“现在有这么一个场景，假如有三种角色，并且存在层级关系，他们需要访问同一个数据源表，但是需要做权限控制，使得每种角色只能看到自己及以下层级的数据。比如：公司有CEO，Manger和普通的employee三种角色，CEO可以查看CEO、Manager和employee层级的数据；Manger只能查看Manger和employee的数据，不能查看CEO层级；而employee只能查看employee的数据，不能查看CEO和Manager级别的数据。这个在SQL Server有比较简单清爽的实现方法吗？”。老鸟这个问题的确问得非常有水准，这个场景也非常普遍，菜鸟顿时陷入了无边的困境。

问题分析

在关系型数据库SQL Server中，权限的确不能达到行列级别这么细粒度的控制，这也是菜鸟为什么陷入困境的原因。但是，突然菜鸟灵魂出窍，灵光一现，像是被雷劈中一般的感觉：虽然SQL Server基于表无法达到那么细粒度的权限控制，但是我们可以建立视图（VIEW），用视图来建立正式表的行、列过滤，然后在视图对象上做权限控制，最终达到对三个层级的权限控制的目的，想到这里菜鸟立马赫然开朗。

解决问题

菜鸟越想越激动，说打就打，说干就干，于是开始了万里长征。

测试环境准备

创建测试数据库Test，接着创建三个用户CEO，Manager和employee，然后创建测试表tb_Test_ViewPermission，最后插入三条测试数据，每个层级一条数据。

IF DB_ID('Test') IS NULL
    CREATE DATABASE Test;
GO

USE Test
GO

--create three logins(CEO, manager, employee)
--create login CEO
IF EXISTS(
            SELECT *
            FROM sys.syslogins
            WHERE name = 'CEO')
BEGIN
      DROP LOGIN CEO;
END
GO
CREATE LOGIN CEO with password='CEODbo',check_policy = off;
GO

--create user CEO
IF USER_ID('CEO') is not null
        DROP USER CEO;
GO
CREATE USER CEO FOR LOGIN CEO;
GO

--create login Manager
IF EXISTS(
            SELECT *
            FROM sys.syslogins
            WHERE name = 'Manager')
BEGIN
      DROP LOGIN Manager;
END
GO
CREATE LOGIN Manager with password='ManagerDbo',check_policy = off;
GO

--create user manager
IF USER_ID('Manager') is not null
        DROP USER Manager;
GO
CREATE USER Manager FOR LOGIN Manager;
GO
       
--create login employee
IF EXISTS(
            SELECT *
            FROM sys.syslogins
            WHERE name = 'employee')
BEGIN
        DROP LOGIN employee;
END
GO
CREATE LOGIN employee with password='employeeDbo',check_policy = off;
GO

--create user employee
IF USER_ID('employee') is not null
        DROP USER employee
GO
CREATE USER employee FOR LOGIN employee;
GO

--create basic TABLE
IF OBJECT_ID('dbo.tb_Test_ViewPermission','u')is not null
    DROP TABLE dbo.tb_Test_ViewPermission
;
GO
CREATE TABLE dbo.tb_Test_ViewPermission
(
        id int identity(1,1) not null primary key
        ,name varchar(20) not null
        ,level_no int not null
        ,title varchar(20) null
        ,viewByCEO char(1) not null
        ,viewByManager char(1) not null
        ,viewByEmployee char(1) not null
        ,salary decimal(9,2) not null
);

--data init.
INSERT INTO dbo.tb_Test_ViewPermission
SELECT 'AA',0,'CEO','Y','Y','Y',1000000.0
union all
SELECT 'BB',1,'Manager','Y','Y','Y',100000.0
union all
SELECT 'CC',2,'employee','Y','Y','Y',10000.0
;
GO

创建三个视图

表对象和数据准备完毕后，接着我们建立三个视图，分别过滤出自己所在层级及以下层级的数据。比如，CEO包含CEO、Manager和employee层级数据；Manger包含Manger和employee层级数据；employee仅包含employee层级数据。

USE Test
GO
--create views for CEO querying, CEO can get all the data
IF OBJECT_ID('dbo.v_employeeinfo_forCEO','v')is not null
        DROP VIEW dbo.v_employeeinfo_forCEO
;
GO
CREATE VIEW dbo.v_employeeinfo_forCEO
AS
SELECT *
FROM dbo.tb_Test_ViewPermission WITH(NOLOCK)
WHERE level_no >= 0;
GO

--create views for Manager querying, Manger can get manger group & employee group data
IF OBJECT_ID('dbo.v_employeeinfo_forManager','v')is not null
        DROP VIEW dbo.v_employeeinfo_forManager
;
Go
CREATE VIEW dbo.v_employeeinfo_forManager
AS
SELECT 
        name
        ,level_no
        ,title
        ,viewByManager
        ,viewByEmployee
        ,salary
FROM dbo.tb_Test_ViewPermission WITH(NOLOCK)
WHERE level_no >= 1; 
GO

--create views for Employee querying, employee just can get employee group data
IF OBJECT_ID('dbo.v_employeeinfo_forEmployee','v')is not null
        DROP VIEW dbo.v_employeeinfo_forEmployee
;
GO
CREATE VIEW dbo.v_employeeinfo_forEmployee
AS
SELECT 
        name
        ,level_no
        ,title
        ,viewByEmployee
        ,salary
FROM dbo.tb_Test_ViewPermission WITH(NOLOCK)
WHERE  level_no >= 2;
GO

权限设置

所有视图创建完毕后，接下来是最为关键的步骤，就是对视图权限的设置。基本的思路是：拿掉所有用户对于基表的权限，对于视图需要拿掉自己以下层级用户权限，然后给予视图自己层级用户的查看权限。比如：Manager层级视图dbo.v_employeeinfo_forManager需要拿掉employee的权限，授予Manager查询权限。

USE Test
GO
--====permission init.
--deny all permission to user for TABLE
DENY ALL ON dbo.tb_Test_ViewPermission TO CEO;
DENY ALL ON dbo.tb_Test_ViewPermission TO Manager;
DENY ALL ON dbo.tb_Test_ViewPermission TO employee;

--deny permission for Manager & employee
DENY ALL ON dbo.v_employeeinfo_forCEO TO Manager;
DENY ALL ON dbo.v_employeeinfo_forCEO TO employee;

DENY ALL ON dbo.v_employeeinfo_forManager TO employee;

--Grant query permission for CEO & Manager & Employee
GRANT SELECT ON dbo.v_employeeinfo_forCEO TO CEO;

GRANT SELECT ON dbo.v_employeeinfo_forManager TO Manager;

GRANT SELECT ON dbo.v_employeeinfo_forEmployee TO employee;
GO

权限测试

以上所有工作准备完毕后，接下来就是最紧张的权限验证环节了，时间才是检验真理的唯一标准。

CEO权限测试

按照预期，CEO应该不能访问基表数据，会报告异常，但是可以查询CEO，manager和employee层级数据，总共三条。测试语句如下，将SSMS的结果显示切换为text模式，或者直接快捷键ctrl + t。

--CEO query test
USE test
GO

--CEO cann't read data from basic table
SELECT *
FROM dbo.tb_Test_ViewPermission WITH(NOLOCK)

--CEO all read the data from CEO group
SELECT 
        CAST(CURRENT_USER AS VARCHAR(10)) AS 'Who am i'
        ,*
FROM v_employeeinfo_forCEO WITH(NOLOCK)
GO

结果显示如下，测试结果的确与预期吻合。

Manager权限测试

预期是Manger对基表没有访问权限，也没有CEO视图的访问权限，但是可以查看到Manger和普通employee的数据，也就是会返回两条数据。

--Manager query test
use test
GO

--Manager cann't read data from basic table
SELECT *
FROM dbo.tb_Test_ViewPermission WITH(NOLOCK)

--Manager can't read the data from CEO group
SELECT *
FROM v_employeeinfo_forCEO WITH(NOLOCK)
GO

--manager can read data from manager group
SELECT 
        CAST(CURRENT_USER AS VARCHAR(10)) AS 'Who am i'
        ,*
FROM dbo.v_employeeinfo_forManager WITH(NOLOCK)
GO

查询结果展示如下，测试结果再次与预期吻合。

Employee权限测试

预期是employee没有基表权限，没有CEO视图查看权限，也没有Manager视图查询权限，只能看到employee层级数据，也就是会返回一条数据。

--Employee query test
USE test
GO

--Employee cann't read data from basic table
SELECT *
FROM dbo.tb_Test_ViewPermission WITH(NOLOCK)

--Employee can't read the data from CEO group
SELECT *
FROM v_employeeinfo_forCEO WITH(NOLOCK)
GO

--Employee can't read data from manager group
SELECT 
        CAST(CURRENT_USER AS VARCHAR(10)) AS 'Who am i'
        ,*
FROM dbo.v_employeeinfo_forManager WITH(NOLOCK)
GO

--Employee just can read data from employee group
SELECT 
        CAST(CURRENT_USER AS VARCHAR(10)) AS 'Who am i'
        ,*
FROM dbo.v_employeeinfo_forEmployee  WITH(NOLOCK)
GO

结果显示如下，employee层级测试结果也完全满足预期。