Oracle(merge)

目的：使用merge完成指定数据引用（包括更新和添加）

使用merge之前的productinfo和productinfo1数据：

PRODUCTID  PRODUCTNAME          PRODUCTPRICE   QUANTITY CATEGORY
---------- -------------------- ------------ ---------- ----------
DESPERATION
--------------------------------------------------------------------------------
ORIGIN
----------
2          head first java                52       2019 book
tecnology
UA

1          computer                     5000         50 electrical
hp_zhan66pro
shanghai

PRODUCTID  PRODUCTNAME          PRODUCTPRICE   QUANTITY CATEGORY
---------- -------------------- ------------ ---------- ----------
DESPERATION
--------------------------------------------------------------------------------
ORIGIN
----------

3          oracle                         80       3000 book
it
UA

4          dubbo                          80       5000 book
it

PRODUCTID  PRODUCTNAME          PRODUCTPRICE   QUANTITY CATEGORY
---------- -------------------- ------------ ---------- ----------
DESPERATION
--------------------------------------------------------------------------------
ORIGIN
----------
UA


SQL> select * from productinfo1;

PRODUCTID  PRODUCTNAME          PRODUCTPRICE   QUANTITY CATEGORY
---------- -------------------- ------------ ---------- ----------
DESPERATION
--------------------------------------------------------------------------------
ORIGIN
----------
1          iphone                       2000       3000 electrical
iphone_x
shanghai

3          oracle                         80       1836 book
it
UA

PRODUCTID  PRODUCTNAME          PRODUCTPRICE   QUANTITY CATEGORY
---------- -------------------- ------------ ---------- ----------
DESPERATION
--------------------------------------------------------------------------------
ORIGIN
----------




目的：完成productinfo1表的数据添加和更新（对比productinfo），相同id的quantity更新成productinfo表的，没有的productinfo表中id的数据，全部记录添加到productinfo1表中；

实现语句：

SQL> merge into productinfo1 using productinfo on (productinfo1.productid=productinfo.productid) when matched then update
  2  set productinfo1.quantity=productinfo.quantity when not matched then insert
  3  values (productinfo.productid,productinfo.productname,productinfo.productprice,productinfo.quantity,productinfo.category,productinfo.desperation,productinfo.origin);
4 行已合并。


实现后的productinfo1表：

SQL> select * from productinfo1;

PRODUCTID PRODUCTNAME PRODUCTPRICE QUANTITY CATEGORY
---------- -------------------- ------------ ---------- ----------
DESPERATION
--------------------------------------------------------------------------------
ORIGIN
----------
1 iphone 2000 50 electrical
iphone_x
shanghai

3 oracle 80 3000 book
it
UA

4 dubbo 80 5000 book
it
UA

2 head first java 52 2019 book
tecnology

语句：merge into productinfo1 using productinfo on (productinfo1.productid=productinfo.productid) when matched then update
2 set productinfo1.quantity=productinfo.quantity when not matched then insert
3 values (productinfo.productid,productinfo.productname,productinfo.productprice,productinfo.quantity,productinfo.category,productinfo.desperation,productinfo.origin);

注意：

1.matched是update,not matched是insert
2.目标表using来源表
3.values后面对应的是来源表的字段，对应字段的数据添加到目标表

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