SQL NULL Explained: IS NULL vs = NULL in Simple Words

[Rajeev Bagra]

Q: What happens if I write debut = NULL in SQL to find missing debut values?
A: It won’t work as expected. The query will usually return zero rows, even if there are missing values.

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Q: Why doesn’t debut = NULL work?
A: Because in SQL, NULL means “unknown / missing”, and SQL cannot compare unknown values using =.

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Q: What is the correct way to find rows where debut is missing?
A: Use IS NULL like this:

SELECT id
FROM players
WHERE debut IS NULL;

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Q: How do I find rows where debut is NOT missing?
A: Use IS NOT NULL:

SELECT id
FROM players
WHERE debut IS NOT NULL;

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✅ Quick Tip:
Whenever you want to check for missing values in SQL, always use IS NULL or IS NOT NULL, not =.

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