MySQL 小数类型超出范围错误

Question

这段代码:

DROP DATABASE IF EXISTS `my_db`;
CREATE DATABASE `my_db`; 
CREATE TABLE `my_db`.`my_table` (
    `id` integer NOT NULL AUTO_INCREMENT, 
    `multiplier` decimal(18, 10) NOT NULL, 
    PRIMARY KEY (`id`)
) Engine=InnoDB;

INSERT INTO `my_db`.`my_table` (`multiplier`) VALUES (100000000.0);

返回错误:

Error Code: 1264. Out of range value for column 'multiplier' at row 1

为什么？逗号之前只有 9 位数字，而该列应该工作到 18 位数字 - 或者我在这里遗漏了一些东西？谢谢。

Answer 1

decimal(18, 10) 表示小数点后 10 位、小数点前 8 位，直到 18 位

https://dev.mysql.com/doc/refman/5.1/en/precision-math-decimal-characteristics.html

For example, a DECIMAL(18,9) column has nine digits on either side of the decimal point, so the integer part and the fractional part each require 4 bytes. A DECIMAL(20,6) column has fourteen integer digits and six fractional digits. The integer digits require four bytes for nine of the digits and 3 bytes for the remaining five digits. The six fractional digits require 3 bytes.