Null Value is a marker for data that has not been entered or is missing, unknown, or inapplicable.

Null Value is a marker for data that has not been entered or is missing, unknown, or inapplicable.

• A. A value present in every field
• B. A marker for a zero value
• C. A marker for a reference to another row
• D. A marker for data that has not been entered or is missing, unknown, or inapplicable

Answer: (D)

Null values indicate missing or inapplicable information in a database. They represent data that hasn’t been entered, is unknown, or does not apply. This is different from zero or an blank string, which are real values, and it’s not a marker for a reference to another row. In SQL, you check for these with IS NULL or IS NOT NULL because any arithmetic or comparison involving NULL yields NULL (unknown). This concept aligns with describing a marker for data that hasn’t been entered or is missing, unknown, or inapplicable.

Null values indicate missing or inapplicable information in a database. They represent data that hasn’t been entered, is unknown, or does not apply. This is different from zero or an blank string, which are real values, and it’s not a marker for a reference to another row. In SQL, you check for these with IS NULL or IS NOT NULL because any arithmetic or comparison involving NULL yields NULL (unknown). This concept aligns with describing a marker for data that hasn’t been entered or is missing, unknown, or inapplicable.