SQL Data Constraints Quiz

What does the NOT NULL constraint ensure?

• The column can have multiple values

• The column cannot have a NULL value

• The column must have a default value

• The column can only contain unique values

When should you use the UNIQUE constraint?

• When a column should have distinct values

• When a column can accept NULL values

• When a column must have a default value

• When a column is a foreign key

What is the purpose of a PRIMARY KEY?

• To allow duplicate values in a column

• To uniquely identify each row in a table

• To set a default value for a column

• To link two tables together

What does a FOREIGN KEY do?

• Ensures a column cannot be NULL

• Automatically increments a column value

• Sets a default value for a column

• Links a column to the primary key in another table

What happens if you try to insert a record with a duplicate PRIMARY KEY?

• The record is inserted successfully

• The insertion fails

• The database ignores the duplicate

• The duplicate value is automatically changed

What does the DEFAULT constraint do?

• Links two tables together

• Ensures all values in a column are unique

• Sets a default value for a column

• Prevents NULL values in a column

When is the CHECK constraint used?

• To automatically generate unique values

• To ensure a column value satisfies a specific condition

• To prevent NULL values in a column

• To link a column to another table

What does the AUTO_INCREMENT attribute do?

• Sets a default value for a column

• Prevents NULL values in a column

• Automatically generates a unique value for a column

• Ensures all values in a column are unique

Which of the following is NOT a type of data constraint in SQL?

• REQUIRED

• NOT NULL

• UNIQUE

• DEFAULT

What is the result of inserting a record with an age of 70 in a table with a CHECK constraint for age between 18 and 65?

• The age is set to NULL

• The record is inserted successfully

• The insertion fails

• The age is automatically adjusted to 65