MySQL MID() 函数

从字符串中提取子字符串（从位置 5 开始，提取 3 个字符）：

SELECT MID("SQL Tutorial", 5, 3) AS ExtractString;

定义和用法

MID() 函数从字符串中提取子字符串（从任意位置开始）。

笔记：MID() 和SUBSTR()函数等于子串()功能。

MID( string, start, length)

Parameter	Description
string	Required. The string to extract from
start	Required. The start position. Can be both a positive or negative number. If it is a positive number, this function extracts from the beginning of the string. If it is a negative number, this function extracts from the end of the string
length	Required. The number of characters to extract

工作于：	从 MySQL 4.0 开始