MyBatis Merge into batch usage issues

All data in insert and update needs to be obtained from the using, so that the batch merge into effect is achieved
MERGE into Tm_user_cart_info T1
USING
(
<foreach collection= "List" item= "item" index= "index" separator= "union" >
SELECT
Case when TEMP1. F_CART_ID is NULL and then TEMP. f_cart_id ELSE TEMP1. f_cart_id END f_cart_id,
TEMP. F_goods_num,
TEMP. F_USER_ID,
TEMP. F_region_num,
TEMP. F_channel_num,
TEMP. F_goods_count
From
(SELECT #{cartid} f_cart_id,#{goodsnum} F_goods_num,#{userid} F_user_id,#{regionnum} F_region_num,#{channelnum} F_ Channel_num,#{goodscount} F_goods_count from DUAL) TEMP
Left JOIN
(
SELECT * from Tm_user_cart_info T2
WHERE 1=1 and T2. f_user_id = #{userid}
and T2. F_goods_num = #{goodsnum}
and T2. F_region_num = #{regionnum}
and T2. F_channel_num = #{channelnum}
And not EXISTS (SELECT "from Tm_user_cart_market T3 WHERE T3. f_cart_id = T2. F_CART_ID)
) TEMP1 on TEMP1. F_goods_num = TEMP. F_goods_num
</foreach>
) T
On (T1. f_cart_id = t.f_cart_id)
When matched then
UPDATE SET T1. F_goods_count = T1. F_goods_count + T.f_goods_count, T1. F_update_time = (SELECT to_char (sysdate, ' Yyyymmddhh24miss ') from DUAL)
When isn't matched then
INSERT
(f_cart_id, F_channel_num, F_merchant_num, f_user_id, F_goods_num, F_goods_count, F_add_time, F_REGION_NUM)
VALUES
(t.f_cart_id, T.f_channel_num, ", t.f_user_id, T.f_goods_num, T.f_goods_count,

(SELECT to_char (sysdate, ' Yyyymmddhh24miss ') from DUAL), T.f_region_num)

#{xxxx} changed to #{item.xxxx}

Reprinted from: http://bbs.csdn.net/topics/390940098