WHERE

What it is

WHERE filters individual rows before grouping.

When to use it

Combine business conditions with explicit null handling.

Syntax

WHERE user_id = ? AND status IN (?, ?)

Example

SELECT id, total_cents FROM orders
WHERE user_id = 7
  AND status IN ('pending', 'paid')
  AND deleted_at IS NULL;

Common mistakes

Use IS NULL, not = NULL; parentheses matter when combining AND and OR.

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