spring_demo/mybatis_train/src/main/resources/mapper/AccountMapper.xml

<?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.mapper.AccountMapper">
    <select id="findAll" resultType="com.pojo.entity.AccountEntity"
            parameterType="java.lang.Integer"
    >
        select id,user_name,balance from account where id= #{id}
    </select>
    <update id="updateOne" parameterType="com.pojo.entity.AccountEntity">
        update account set user_name = #{user_name} where id = #{id}
    </update>
    <insert id="insertOne" parameterType="com.pojo.entity.AccountEntity">
        insert into account(user_name,balance) value (#{user_name},#{balance})
    </insert>
</mapper>