<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.casic.missiles.mapper.MeterFixedAssetsMapper"> <select id="selectMaxNo" resultType="java.lang.Long"> SELECT IFNULL(max(RIGHT(asset_no, 12)), 0) from meter_fixed_assets </select> </mapper>