MCQ IN COMPUTER SCIENCE & ENGINEERING

Detailed explanation-1: -The NOT NULL constraint enforces a column to NOT accept NULL values. This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.

Detailed explanation-2: -The NOT NULL constraint is used to ensure that a given column of a table is never assigned the null value. Once a NOT NULL constraint has been defined for a particular column, any insert or update operation that attempts to place a null value in that column will fail.

Detailed explanation-3: -Use the NULL keyword to specify that a column can store the NULL value for its data type. This implies that the column need not receive any value during insert or update operations. The NULL constraint is logically equivalent to omitting the NOT NULL constraint from the column definition.

Detailed explanation-4: -What is the function of the not null constraint? Explanation: The not null constraint ensures that data is entered into the database. It displays an error message whenever a data field mentioned is left empty.

Detailed explanation-5: -A NOT NULL constraint is a rule that prevents null values from being entered into one or more columns within a table. A unique constraint (also referred to as a unique key constraint) is a rule that forbids duplicate values in one or more columns within a table.