In this article I would like to explain about “Constraints”. Constrains are one of the key factor in designing a table. Before I explain what is the use of constrains lets take one real world example. When you are opening a bank account bank says, you need to maintain minimum balance of 1000 in your account. This is a business rule. There are several places to implement this rule. We can implement this in Front-End application or in the Back-end code.