方法一：

<update id="updateListPO">       <foreach collection="list" separator=";" item="item">UPDATE project_quotation_item<SET>product_num = #{item.productNum},product_price_total = #{item.productPriceTotal},product_price_wttax = #{item.productPriceWttax},certificate = #{item.certificate},deliver_date = #{item.deliverDate},product_brand = #{item.productBrand},producer = #{item.producer},exp = #{item.exp},is_deleted = #{item.isDeleted},remark = #{item.remark},substitute_type = #{item.substituteType},<if test='null != item.quotationStatus and "" != item.quotationStatus and "null" != item.quotationStatus'>quotation_status = #{item.quotationStatus},</if></set>WHEREid = #{item.id}</foreach>
</update>

方法二：（优化后的）

<update id="updateListPO">update project_quotation_item<set><trim prefix="product_num = case" suffix="end,"><foreach collection="list" item="item"><if test='null != item.productNum and "" != item.productNum and "null" != item.productNum'>when id=#{item.id} then #{item.productNum}</if></foreach></trim><trim prefix="product_price_total = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.productPriceTotal}</foreach></trim><trim prefix="product_price_wttax = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.productPriceWttax}</foreach></trim><trim prefix="certificate = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.certificate}</foreach></trim><trim prefix="deliver_date = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.deliverDate}</foreach></trim><trim prefix="product_brand = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.productBrand}</foreach></trim><trim prefix="producer = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.producer}</foreach></trim><trim prefix="exp = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.exp}</foreach></trim><trim prefix="is_deleted = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.isDeleted}</foreach></trim><trim prefix="remark = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.remark}</foreach></trim><trim prefix="substitute_type = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.substituteType}</foreach></trim><trim prefix="quotation_status = case" suffix="end,"><foreach collection="list" item="item">when id=#{item.id} then #{item.quotationStatus}</foreach></trim></set><where>id in<foreach collection="list" separator="," item="item" open="(" close=")">#{item.id}</foreach></where></update>

方法三：

<update id="updateBatch">update T t<trim prefix="set" suffixOverrides=","><trim prefix="t.updateTime = case" suffix="end,"><foreach collection="list" item="item" index="index"><if test="item.updateTime != null">when t.id = #{item.id} then #{item.updateTime}</if></foreach></trim><trim prefix="t.updateBy = case" suffix="end,"><foreach collection="list" item="item" index="index"><if test="item.updateBy != null">when t.id = #{item.id} then #{item.updateBy}</if></foreach></trim><trim prefix="t.remark = case" suffix="end,"><foreach collection="list" item="item" index="index"><if test="item.remark != null">when t.id = #{item.id} then #{item.remark}</if></foreach></trim></trim>where<foreach collection="list" item="item" index="index" open="t.id in (" separator="," close=")">#{item.id}</foreach>
</update>