Easy SQL Question 44 of 226

What does NULL mean in SQL, and why is NULL = NULL not TRUE?

Java Specialist · Speak this in 60–90 seconds · Faridabad & Delhi NCR

Mean3.25average

Median2middle

Mode2most often

NULL means unknown or missing, not the integer zero or empty string.

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Keep it short, concrete,

and tied to Backend work.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

Before you speak the answer, walk the interviewer through these steps:

1
NULL means unknown or
missing, not the integer zero or empty string.
2
Comparisons with NULL yield
UNKNOWN, so you write IS NULL or IS NOT NULL.
3
Aggregate functions skip NULLs,
which surprises people counting a column versus counting rows.
4
Give an example
One tiny concrete case you can say aloud.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

Here's a short line you can speak, broken into clear beats:

Say this line

“Comparisons with NULL yield UNKNOWN, so you write IS NULL or IS NOT NULL.”

Break into beats

ComparisonswithNULLyieldUNKNOWNso

Speaking order

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Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

NULL means unknown or missing, not the integer zero or empty string. Comparisons with NULL yield UNKNOWN, so you write IS NULL or IS NOT NULL.