Super key

A set or collection of one or more attributes or fields (column), which uniquely identify a row or tuple in a relation or table is known as super key.

Lets consider, a relation called Emp

The above table has many super key s and those super keys are able to uniquely identify a tuple of the employee table.

• {Emp_No}
• {Emp_SSN}
• {Emp_SSN, Emp_Name}
• {Emp_SSN, Emp_No}
• {Emp_No, Emp_Name}
• {Emp_SSN, Emp_No, Emp_Name}