Question

Rashmi is not able to leave a blank in the Salary column of the Employee table. Which constraint is applied on the field Salary?

• A. NOT NULL
• B. DEFAULT
• C. CHECK
• D. NOT BLANK

Hint:

Use NOT NULL to ensure that a field must always be filled — no empty entries allowed.

Answer 1

The Correct Option is A

In relational databases, the NOT NULL constraint is used to ensure that a particular column cannot be left empty.
When the NOT NULL constraint is applied to the Salary column, it guarantees that every record must have a value entered for salary.
This is crucial in cases where missing data would be unacceptable, such as financial records or unique identifiers.
- DEFAULT assigns a default value to a column if no value is provided but does not enforce non-blank entries.
- CHECK is used to validate values against a condition but does not prevent NULL values by itself.
- NOT BLANK is not a standard SQL constraint.
Hence, option (A) is the correct answer as it ensures the Salary column cannot be left blank.