mybatis使用case when按照条件进行更新方式

<update id="updatenrpurchaseorderdetailbygoodsbarcode">
    update nr_purchase_order_detail
    set stored_num =
    <foreach collection="barcodelist" item="item" index="index"
             separator=" " open="case goods_barcode" close="end">
        when #{item.barcode} then stored_num + #{item.receivenum}
    </foreach>
    ,unstored_num =
    <foreach collection="barcodelist" item="item" index="index"
             separator=" " open="case goods_barcode" close="end">
        when #{item.barcode} then actual_goods_num - stored_num
    </foreach>
    where goods_barcode in
    <foreach collection="barcodelist" item="item" index="index" separator="," open="(" close=")">
        #{item.barcode}
    </foreach>
    and parent_id = #{id}
</update>

<!--casewhen形式更新-->
<update id="testcasewhen" parametertype="java.util.map">
    update ${user}
    <set>
        <trim prefix="id= case id" suffix="end,">
            <foreach collection="list" item="param">
                <if test="param.id != null and id != ''">
                    when #{param.id} then #{param.id}
                </if>
            </foreach>
        </trim>
        <trim prefix="username = case id" suffix="end,">
            <foreach collection="list" item="param">
                <if test="param.username != null and param.username != ''">
                    when #{param.} then #{param.username}
                </if>
            </foreach>
        </trim>
        <trim prefix="password = case id" suffix="end,">
            <foreach collection="list" item="param">
                <if test="param.password != null and param.password != ''">
                    when #{param.id} then #{param.password}
                </if>
            </foreach>
        </trim>
    </set>
    <where>
        id in
        <foreach collection="list" item="param" separator="," open="(" close=")">
            #{param.id}
        </foreach>
    </where>
</update>