<?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.itsoku.lesson012.mapper.AccountMapper">

    <!-- 余额增加 -->
    <update id="balanceAdd">
        update t_account set balance = balance + #{price} where id = #{accountId} and #{price}>0
    </update>

</mapper>