Introduction to constraints in SQL Language

Asked By James S Savoy 5 points N/A Posted on - 03/30/2016

What does constraints in SQL mean? Which are the different types of Integrity Constraints? What happens if a constraint is violated?

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Answered By Paul M Lucero 5 points N/A #183289

Introduction to constraints in SQL Language

Hi

 Constraints are some rules/ restrictions specified by the user in order to enter values within a determined range or not allowing the user to enter data containing a particular type of input. There are three types of Integrity constraints:

• Domain Integrity Constraint

• Entity Integrity Constraint

• Referential Integrity Constraint

When any of the constraints mentioned by the database developer are violated, a message appears on the screen saying that a constraint was violated with the name of the constraint that was violated so that the user gets to know what types of values he/she is allowed to enter into the database.

 

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• Posted on - 03/30/2016
• Question Category: ProgScripting Languages