The NOT NULL constraint ensures that a column cannot store NULL values.
It forces users to enter a value.
This helps maintain complete data.
When NOT NULL is applied, the column must always contain a value.
Empty entries are not allowed.
NOT NULL is commonly used for important fields such as name, email, or username.
These fields must always be filled.
If a NULL value is inserted, the database will reject the operation.
This prevents incomplete records.
NOT NULL improves data quality.
It ensures required fields are never empty.
This constraint is widely used in real applications.