2.12f

What is a column constraint in a CREATE TABLE statement?

It appears in a separate clause and governs values in a single column.

What does the NOT NULL constraint do?

It prohibits null values in a column.

What is the purpose of a DEFAULT constraint?

It specifies a value that is inserted when a column is omitted from an INSERT statement.

What is a PRIMARY KEY constraint?

It is a constraint that uniquely identifies each record in a table and can be applied to a column or group of columns.

What does the UNIQUE constraint do?

It ensures that all values in a column are different from one another.

What is a CHECK constraint?

It is a table constraint that ensures that the specified condition is satisfied for values in specified columns.

How is a constraint named in a table?

Using the CONSTRAINT keyword followed by the constraint name in the declaration.

What happens when a foreign key constraint refers to a primary key of a table that is being dropped?

Dropping the table fails unless the foreign key constraint is removed first.

What is the purpose of the ALTER TABLE statement?

To add, drop, or change constraints in an existing table.

Can CHECK column constraints be named?

Yes, a CHECK column constraint can be named with a CONSTRAINT clause in the column declaration.