SpringBoot/src/main/resources/mapper/UserMapper.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.example.springboot.mapper.UserMapper">
    <update id="update">
        update user
        <set>
            <if test="name != null">
                name = #{name},
            </if>
            <if test="sex != null">
                sex = #{sex},
            </if>
            <if test="stature != null">
                stature = #{stature},
            </if>
            <if test="mail != null">
                mail = #{mail},
            </if>
            <if test="pwd != null">
                pwd = #{pwd}
            </if>
            <if test="phone != null">
                phone = #{phone}
            </if>
        </set>
        <where>
            id = #{id}
        </where>
    </update>
</mapper>