This feature is new, starting from version SQL Server 2016. Row-level security was a security challenge for a long time. It was implemented through different sets of add-ons and tools. However, this is now built into the database engine and SQL language. Imagine this scenario: a sales person has read permission on the Sales table, but you want each sales person to only see their own sales records, and the manager should see all the records. If you look at this problem through the classic user-permission chain, it is impossible to implement it. However, the row-level security feature makes it possible.
Let's see how it works:
1> USE Sandbox 2> GO --Create three users without logins 1> CREATE USER Manager WITHOUT LOGIN; 2> CREATE USER Sales1 WITHOUT LOGIN; 3> CREATE USER Sales2 WITHOUT LOGIN; 4> GO
-- Create Sales table 1> CREATE TABLE...