Computer Science for IGCSE & O level - Databases (Section 3 - No. 9)
Which of the following is true about primary keys?
They can contain duplicate values.
They uniquely identify each record in a table.
They cannot be null.
They are used for sorting.
Εξήγηση
Primary keys must be unique and cannot contain null values, ensuring that each record in the table can be distinctly identified.