<update id="update" parameterType="User">
        update user
        <set>
            <if test="name!=null">
                name=#{name},
            </if>
            <if test="phone!=null">
                phone=#{phone},
            </if>
            <if test="aboutme!=null">
                aboutme=#{aboutme},
            </if>
            <if test="password!=null">
                password=#{password},
            </if>
            <if test="avatar!=null">
                avatar=#{avatar},
            </if>
            <if test="type!=null">
                type=#{type},
            </if>
            <if test="enable!=null">
                enable=#{enable},
            </if>
            <if test="agencyId!=null">
                agency_id=#{agencyId}
            </if>
            where id=#{id}
        </set>
    </update>

更新语法后面set if判断语句后面有个， 但是如果agencyId为空
语句变成
update set name = “xiaoxiao”, where id=1
set语句有个逗号会报错 这个要怎么解决