mybatis的set标签

<update id="editTransport" parameterType="java.util.Map">
    update hl_transport_info
    <set>
        <if test="transportNo != null and transportNo != ''">transport_no = #{transportNo},</if>
        <if test="upChain != null and upChain != ''">up_Chain = #{upChain},</if>
        <if test="outTime != null and outTime != ''">
            <!--out_Time = #{outTime,jdbcType=DATE},-->
            and DATE_FORMAT(out_Time, '%Y-%m-%d') =  DATE_FORMAT(#{outTime}, '%Y-%m-%d'),
        </if>
    </set>
    where id = #{id}
</update>