Computer Science for IGCSE & O level - Databases (Section 3 - No. 20)
What does the 'NOT NULL' constraint ensure in a database?
That a field contains a specific value.
That a field does not contain any spaces.
That a field must have a value.
That a field can be left empty.
คำอธิบาย
The NOT NULL constraint prevents a field from being assigned a NULL value.