mybatis

Posted 2021-03-02 若梦plus

mybatis update

使用场景：当使用update进行更新的时候，数据表难免会有些不被更新的字段，如create_time，这些字段只想保留第一次插入进表的值，在后续更新sql语句中，只想更新需要被更新的字段。

解决办法1：

<!--更新收货地址-->
  <update id="updateByShipping" parameterType="com.mall.pojo.Shipping">
    update mall_shipping
    set
    receiver_name = #{receiverName,jdbcType=VARCHAR},
    receiver_phone = #{receiverPhone,jdbcType=VARCHAR},
    receiver_mobile = #{receiverMobile,jdbcType=VARCHAR},
    receiver_province = #{receiverProvince,jdbcType=VARCHAR},
    receiver_city = #{receiverCity,jdbcType=VARCHAR},
    receiver_district = #{receiverDistrict,jdbcType=VARCHAR},
    receiver_address = #{receiverAddress,jdbcType=VARCHAR},
    receiver_zip = #{receiverZip,jdbcType=VARCHAR},
    <if test="createTime != null">
      create_time = #{createTime,jdbcType=TIMESTAMP},
    </if>
    update_time = now()
    where id = #{id,jdbcType=INTEGER}
    and user_id = #{userId,jdbcType=INTEGER}
  </update>

解决办法2（优化）

<update id="updateUser" parameterType="com.test.entity.User">
        update BS_USER
            <trim prefix="set" suffixOverrides=",">
                <if test="ACCOUNT != null">ACCOUNT=#{ACCOUNT},</if>
                <if test="NAME != null">NAME=#{NAME},</if>
                <if test="PROV != null">PROV=#{PROV},</if>
                <if test="FAILURE_TIME != null">FAILURE_TIME=#{FAILURE_TIME},</if>
            </trim>
        where USERID=#{USERID}
    </update>

这种方法是将set标签换成<trim prefix="set"><trim>

标签中的suffixOverrides=","是去掉最后一个if后面的逗号，防止在动态更新多个参数，使用多个if的时候，因为最后一个逗号出现问题。