A database object (data integrity mechanism) that ensures that each value within a column or combination of columns is unique.
Uniquely identifies each row of a table and can contain a null.
An internally used 4-byte column that SQL Server’s database engine automatically adds to a row to make each index key unique.
Data that has no metadata, such as text files.
A database role created by the DBA.
A custom function written by developers in SQL Server.