Question

What database key uniquely identifies each record on a table?

Answer 1

Answer:

A Primary key uniquely identifies each record in a table and must never be the same for the 2 records. Primary key is a set of one or more fields ( columns) of a table that uniquely identify a record in database table. A table can have only one primary key and one candidate key can select as a primary key. The primary key should be chosen such that its attributes are never or rarely changed, for example, we can’t select Student_Id field as a primary key because in some case Student_Id of student may be changed.