项目中遇到的merge into的用法

一个项目中要使用merge into的语法更新一张表的数据做复制，速度还是比较快的。

merge into pharmacy.DRUG_PRESC_DETAIL bb    --需要更新的表
using (select * from pharmacy.DRUG_PRESC_DETAIL@server1 c where c.PRESC_DATE >= sysdate -100) dd  --相关联的的表
on(bb.PRESC_DATE = dd.PRESC_DATE and bb.PRESC_NO = dd.PRESC_NO and bb.ITEM_NO = dd.ITEM_NO)       --定义的规则
when matched then
 update 
    set
   bb.DRUG_CODE = dd.DRUG_CODE,
   bb.DRUG_SPEC = dd.DRUG_SPEC,
   bb.DRUG_NAME = dd.DRUG_NAME,
   bb.FIRM_ID = dd.FIRM_ID,
   bb.PACKAGE_SPEC = dd.PACKAGE_SPEC,
   bb.PACKAGE_UNITS = dd.PACKAGE_UNITS,
   bb.QUANTITY = dd.QUANTITY,
   bb.COSTS = dd.COSTS,
   bb.PAYMENTS = dd.PAYMENTS,
   bb.ORDER_NO = dd.ORDER_NO,
   bb.ITEM_SNO = dd.ITEM_SNO,
   bb.ORDER_SUB_NO = dd.ORDER_SUB_NO,
   bb.ADMINISTRATION = dd.ADMINISTRATION,
   bb.FLAG = dd.FLAG
when not matched then
 insert
  values 
   （dd.PRESC_DATE,
   dd.PRESC_NO,
   dd.ITEM_NO,
   dd.DRUG_CODE,
   dd.DRUG_SPEC,
   dd.DRUG_NAME,
   dd.FIRM_ID,
   dd.PACKAGE_SPEC,
   dd.PACKAGE_UNITS,
   dd.QUANTITY,
   dd.COSTS,
   dd.PAYMENTS,
   dd.ORDER_NO,
   dd.ITEM_SNO,
   dd.ORDER_SUB_NO,
   dd.ADMINISTRATION,
   dd.FLAG);
commit;