What is a CHECK constraint in SQL?

What is a CHECK constraint in SQL?

A CHECK constraint is a rule that limits the values that can be placed in a column. It ensures that all values in a column satisfy a specific condition.

Can you give me an example of how to use a CHECK constraint?

Sure! For instance, if you have a table for employees, you can use a CHECK constraint to ensure that the age column only accepts values greater than 18: CREATE TABLE Employees (ID int, Age int CHECK (Age > 18));

What happens if I try to insert a value that violates the CHECK constraint?

If you try to insert a value that violates the CHECK constraint, the database will reject the insertion and return an error message.

Can I have multiple CHECK constraints on a single column?

Yes, you can have multiple CHECK constraints on a single column, and all conditions must be satisfied for the data to be valid.