Logical Operators: AND, OR, NOT

This lesson covers SQL's logical operators — AND, OR, and NOT — so you can combine multiple conditions in a search. It's for anyone searching "SQL AND OR tutorial."

Logical operators combine conditions: AND means "both must be true," OR means "at least one must be true," and NOT negates a condition.

The example uses WHERE score >= 80 AND class_id = 1 to find students who satisfy both "scored 80+" and "is in Class 1" at once — good practice for building conditions more specific than either alone could express.

A common early mistake is misjudging precedence when mixing AND and OR — AND evaluates before OR, so getting the result you intend often requires parentheses to make the grouping explicit, and skipping that step can produce surprising results. Use AND when stacking conditions (like "80+ and Class A"), OR when either one is fine ("Class A or Class B") — and parentheses whenever the logic could otherwise be ambiguous.