What is a primary key in DBMS?
A. A column or combination of columns that uniquely identifies each row in a table
B. A column that contains only unique values
C. A column that cannot contain null values
D. All of the above
Answer:A
What is a primary key in DBMS?
A. A column or combination of columns that uniquely identifies each row in a table B. A column that contains only unique values C. A column that cannot contain null values D. All of the above