Hello and welcome to Working With Constraints, the third course in the Creating Database Structure track.

In this course, you're going to learn a concept which will make it easier to work with data models: constraints.

Constraints are special rules for table data. They tell the database what values are allowed in specific columns – e.g., each salary should be greater than 0, each person should have a name stored in the database, etc. If there is a value which violates the rules, the row won't be added. Constraints are used to keep database data correct.

Let's get started!