关于MERGE问题????

Question

4=2+2
用part_count + shipment.part_count＝4　update了

Answer 1

part_count + shipment.part_count
怎会是2＋2呢
应该是5+2吧

Answer 2

create table inventory (part_no integer, part_count integer);
insert into inventory values(1,5);
insert into inventory values(3,6);create table shipment (part_no integer, part_count integer);
insert into shipment values(1,2);
insert into shipment values(2,2);MERGE INTO inventory
    USING shipment
    ON (inventory.part_no = shipment.part_no)
WHEN MATCHED THEN
   UPDATE SET part_count = part_count + shipment.part_count
WHEN NOT MATCHED THEN
   INSERT VALUES (shipment.part_no,shipment.part_count);commit;select * from inventory;  PART_NO   PART_COUNT
----------              ----------
      1                      7
      3                      6
      2                      2

Answer 3

你执行前先检查inventory和shipment，看里面的记录是什么

Answer 4

检查记录是否正确，检查sql语句是否正确

Answer 5

我将上面的代码COPY了,执行结果还是不对.是不是数据库有问题.http://www.zdnet.com.cn/developer/code/story/0,2000081534,39235314,00.htm

Answer 6

正确的是
select * from inventory;  PART_NO   PART_COUNT
----------              ----------
      1                      4
      3                      6
      2                      2

Answer 7

create table inventory (part_no integer, part_count integer);
insert into inventory values(1,5);
insert into inventory values(3,6);create table shipment (part_no integer, part_count integer);
insert into shipment values(1,8);
insert into shipment values(2,2);执行MERGE后的结果为什么会是:
select * from inventory;  PART_NO   PART_COUNT
----------              ----------
      1                     16
      3                      6
      2                      2

Answer 8

我试一下，不管你怎么写part_count = part_count + shipment.part_count，好像与inventory表没有关系，只与shipment表有关系。

Answer 9

是不是要注明表呀
UPDATE SET part_count = inventory.part_count + shipment.part_count

Answer 10

同意楼上的，注明表果然成了7
SQL> MERGE INTO inventory
  2      USING shipment
  3      ON (inventory.part_no = shipment.part_no)
  4  WHEN MATCHED THEN
  5     UPDATE SET part_count = part_count + shipment.part_count
  6  WHEN NOT MATCHED THEN
  7     INSERT VALUES (shipment.part_no,shipment.part_count);DoneSQL> commit;Commit completeSQL> select * from inventory;                                PART_NO                              PART_COUNT
--------------------------------------- ---------------------------------------
                                      1                                       4
                                      3                                       6
                                      2                                       2
SQL> MERGE INTO inventory
  2      USING shipment
  3      ON (inventory.part_no = shipment.part_no)
  4  WHEN MATCHED THEN
  5     UPDATE SET part_count = inventory.part_count + shipment.part_count
  6  WHEN NOT MATCHED THEN
  7     INSERT VALUES (shipment.part_no,shipment.part_count);DoneSQL> commit;Commit completeSQL> select * from inventory;                                PART_NO                              PART_COUNT
--------------------------------------- ---------------------------------------
                                      1                                       7
                                      3                                       6
                                      2                                       2