| 用途 | 行级过滤 |
|---|---|
| 运算符 | = <> != < <= > >= AND OR NOT BETWEEN IN LIKE |
| 空值 | IS NULL / IS NOT NULL |
条件示例
条件示例
SELECT * FROM orders WHERE status = 'paid';
SELECT * FROM orders WHERE qty BETWEEN 1 AND 10 AND amount > 100;
SELECT * FROM orders WHERE user_id IN (1001, 1002, 1003);
SELECT * FROM orders WHERE remark IS NULL;对索引列做运算或函数（如 WHERE DATE(created_at)='2026-10-12'）会使索引失效，改成范围条件 created_at >= '2026-10-12' AND created_at < '2026-10-13'。