🔎 FilteringbeginnerCommonly used

How to use AND, OR and NOT in SQL

Combine multiple filter conditions in a WHERE clause.

AND — all conditions must matchAll databases

SELECT name, age, country
FROM users
WHERE country = 'Kenya'
  AND age >= 18
  AND active = true;

Every condition must be true for a row to be included.

OR — any condition can matchAll databases

SELECT name, country
FROM users
WHERE country = 'Kenya'
   OR country = 'Nigeria'
   OR country = 'Ghana';

A row is included if any condition is true.

For multiple OR conditions on the same column, use IN instead.

NOT — negate a conditionAll databases

SELECT name, country
FROM users
WHERE NOT (country = 'Kenya' OR country = 'Nigeria');

Excludes rows where either condition is true.

Operator precedence — use parenthesesAll databases

-- AND is evaluated before OR — this may not do what you expect:
SELECT * FROM orders
WHERE status = 'pending' OR status = 'failed' AND amount > 100;

-- Be explicit with parentheses:
SELECT * FROM orders
WHERE (status = 'pending' OR status = 'failed')
  AND amount > 100;

AND has higher precedence than OR. Always use parentheses when mixing AND and OR to make the intent clear.

This is one of the most common SQL bugs.

Common Mistakes

→AND/OR precedence — AND binds tighter than OR. Always use parentheses when mixing them.
→Writing WHERE x = 1 OR 2 — this does not work. Write WHERE x = 1 OR x = 2.

Common Mistakes

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