merge用法

Oracle 中MERGE语句的用法（转载）
http://blog.youkuaiyun.com/lichkui/article/details/4306299

MERGE INTO TD_CART_ITEM T1
USING (SELECT ? AS F_ITEM_ID,
              ? AS F_ITEM_TYPE,
              ? AS F_CHANNEL_ID,
              ? AS F_CUSTOMER_ID,
              ? AS F_QUANTITY,
              case
                when trim(?) is null then
                 '0'
                else
                 trim(?)
              end AS F_EXCHANGE_ID,
              case
                when trim(?) is null then
                 '0'
                else
                 trim(?)
              end AS F_EXCHANGE_NUM
         FROM DUAL) T2
ON (T1.F_CUSTOMER_ID = T2.F_CUSTOMER_ID AND T1.F_ITEM_ID = T2.F_ITEM_ID AND T1.F_CHANNEL_ID = T2.F_CHANNEL_ID and t1.f_item_type = t2.F_ITEM_TYPE and ((t1.f_exchange_id = t2.f_exchange_id and t1.f_exchange_num = t2.F_EXCHANGE_NUM) or (t1.f_exchange_id is null and t1.f_exchange_num is null)))
WHEN MATCHED THEN
  UPDATE
     SET T1.F_QUANTITY = T1.F_QUANTITY + T2.F_QUANTITY
   WHERE T1.F_CUSTOMER_ID = T2.F_CUSTOMER_ID
     AND T1.F_ITEM_ID = T2.F_ITEM_ID
     AND T1.F_CHANNEL_ID = T2.F_CHANNEL_ID
     and t1.f_item_type = t2.F_ITEM_TYPE
     and ((t1.f_exchange_id = t2.f_exchange_id and
         t1.f_exchange_num = t2.F_EXCHANGE_NUM) or
         (t1.f_exchange_id is null and t1.f_exchange_num is null))
WHEN NOT MATCHED THEN
  INSERT
    (F_ITEM_ID,
     F_QUANTITY,
     F_CUSTOMER_ID,
     F_ITEM_TYPE,
     F_CHANNEL_ID,
     F_EXCHANGE_ID,
     F_EXCHANGE_NUM)
  VALUES
    (T2.F_ITEM_ID,
     T2.F_QUANTITY,
     T2.F_CUSTOMER_ID,
     T2.F_ITEM_TYPE,
     T2.F_CHANNEL_ID,
     T2.F_EXCHANGE_ID,
     T2.F_EXCHANGE_NUM);

merge 用法