| 用途 | 数值处理 |
|---|---|
| 常用 | ROUND() CEIL() FLOOR() ABS() MOD() CAST() CONVERT() |
| 场景 | 报表取整、分页游标、类型转换 |
常用示例
常用示例
SELECT ROUND(3.14159, 2) AS pi2, FLOOR(3.9) AS f, CEIL(3.1) AS c;
SELECT MOD(10, 3) AS m, ABS(-12) AS a;
SELECT CAST('2026-10-12' AS DATE) AS d, CAST(12.5 AS SIGNED) AS i;
SELECT 0.1 + 0.2 = 0.3 AS float_eq; -- 浮点不精确，结果为 0钱款与发票金额严禁用 FLOAT/DOUBLE：二进制浮点会出现 0.1+0.2<>0.3 的误差，必须用 DECIMAL。