In this post, I am going to publish about The Row Level Security which is now a common feature of all new version of RDBMSs like SQL Server 2016, PostgreSQL 9.5.

With the concept of Row Level Security, we can restrict the user for a particular set of records.
Previously, we are doing this kind of restriction using by creating filtered VIEWS and assign related VIEWS to relevant Users.

SQL Server 2016 has this Row Level Security feature which extends the overall security policy of the SQL Server.

PostgreSQL 9.5: Row Level Security by Example

Please check the below full demonstration on this.

Create a test database:

CREATE DATABASE CheckRowSecurity;
GO 
USE CheckRowSecurity;
GO

Create a table with sample data:

CREATE TABLE tbl_employeeSalary
(
	empcode VARCHAR(10)
	,empname VARCHAR(10)
	,empsalary BIGINT
	,[month] INT
)
GO
 
INSERT  INTO tbl_employeeSalary
VALUES 
('Anv','Anvesh',150000,1)
,('Anv','Anvesh',120000,2)
,('Anv','Anvesh',160000,3)
,('Anv','Anvesh',170000,4)
,('Mar','Martin',90000,1)
,('Mar','Martin',100000,2)
,('Mar','Martin',120000,3)
,('Mar','Martin',130000,4)
GO

Create two test users and assign SELECT permission on the table:

CREATE USER Anv WITHOUT LOGIN;
CREATE USER Mar WITHOUT LOGIN;
GO

GRANT SELECT ON tbl_employeeSalary TO Anv
GRANT SELECT ON tbl_employeeSalary TO Mar
GO

Create filter predicate function:

CREATE FUNCTION rowLevelSecurity(@userName as sysname)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN SELECT 1 AS rowLevelSecurityResult
WHERE @userName = USER_NAME();
GO

Add filter predicate to the table:

CREATE SECURITY POLICY UserFilter
ADD FILTER PREDICATE dbo.rowLevelSecurity(empcode)
ON dbo.tbl_employeeSalary
WITH (STATE = ON);
GO

Select table without any user:
You will get a blank result set because we alter the security policy of this table.

SELECT * FROM tbl_employeeSalary

Check for User ‘Anv’:

EXECUTE AS USER = 'Anv'
SELECT * FROM tbl_employeeSalary
REVERT
GO

Result:

empcode    empname    empsalary            month
---------- ---------- -------------------- -----------
Anv        Anvesh     150000               1
Anv        Anvesh     120000               2
Anv        Anvesh     160000               3
Anv        Anvesh     170000               4

Check for User ‘Mar’:

EXECUTE AS USER = 'Mar'
SELECT * FROM tbl_employeeSalary
REVERT
GO

Result:

empcode    empname    empsalary            month
---------- ---------- -------------------- -----------
Mar        Martin     90000                1
Mar        Martin     100000               2
Mar        Martin     120000               3
Mar        Martin     130000               4