DB Development Question:
Download Questions PDF

What is difference between primary key and unique key?


Basic difference between primary key and unique is that primary key is used to define a table in other tables for preventing data from anomalies,and unique key is used in a table to apply unifications among different values or columns of a tables and only in that table obviously.Their is no usage of unique key outward a table but primary key is often used to make relations between other tables.

Download DB Development Interview Questions And Answers PDF

Previous QuestionNext Question
How to find the first two highest salaries in deptno in emp table?What is the use of foreginkey?