Question

假设我有2个具有相同结构的表：STOCK和NEW_STOCK。这些表的主键由（ID_DATE，ID_SELLER，ID_INVOICE，ID_DOC）组成。

现在，我需要为每个（ID_DATE，ID_SELLER，ID_INVOICE，ID_DOC）获取有关此要求的金额（字段AMOUNT）：

如果NEW_STOCK中有记录，我会从NEW_STOCK获得AMOUNT，否则，我会从STOCK表中获得AMOUNT。

请注意，ID_DATE和ID_SELLER是给查询的输入，即仅考虑STOCK表的查询将如下所示：

select AMOUNT, ID_DATE, ID_SELLER, ID_INVOICE
    from STOCK
    where ID_DATE = 1
      and ID_SELLER = 'SELL1';

STOCK：

+---------+-----------+------------+--------+--------+
| ID_DATE | ID_SELLER | ID_INVOICE | ID_DOC | AMOUNT |
+---------+-----------+------------+--------+--------+
|       1 |     SELL1 |        IN1 |   DOC1 |    100 |
|       1 |     SELL1 |        IN2 |   DOC2 |     50 |
|       1 |     SELL1 |        IN3 |   DOC3 |     42 |
+---------+-----------+------------+--------+--------+

NEW_STOCK：

+---------+-----------+------------+--------+--------+
| ID_DATE | ID_SELLER | ID_INVOICE | ID_DOC | AMOUNT |
+---------+-----------+------------+--------+--------+
|       1 |     SELL1 |        IN2 |   DOC2 |     12 |
+---------+-----------+------------+--------+--------+

然后，我必须得到以下结果：

+---------+-----------+------------+--------+--------+
| ID_DATE | ID_SELLER | ID_INVOICE | ID_DOC | AMOUNT |
+---------+-----------+------------+--------+--------+
|       1 |     SELL1 |        IN1 |   DOC1 |    100 |
|       1 |     SELL2 |        IN2 |   DOC2 |     12 |
|       1 |     SELL3 |        IN3 |   DOC3 |     42 |
+---------+-----------+------------+--------+--------+

ps：我正在研究Oracle 10。

Answer 1

使用外连接和NVL（arg1，arg2）功能。如果它不是NULL，则返回第一个参数，否则返回第二个参数。例如：

select s.AMOUNT, s.ID_DATE, s.ID_SELLER, s.ID_INVOICE,
   NVL(n.AMOUNT, s.AMOUNT) amount       
from STOCK s, NEW_STOCK n
where s.ID_DATE = n.ID_DATE(+) 
  and s.ID_SELLER = n.ID_SELLER(+)
  and s.ID_INVOICE = n.ID_INVOICE(+)
  and s.ID_DOC = n.ID_DOC(+)
  and s.ID_DATE = 1
  and s.ID_SELLER = 'SELL1';

如果您发现它更具可读性，则可以使用LEFT OUTER JOIN语法而不是(+)。我从v7开始使用Oracle，我更喜欢(+)。

这是LEFT OUTER JOIN语法：

select s.AMOUNT, s.ID_DATE, s.ID_SELLER, s.ID_INVOICE,
   NVL(n.AMOUNT, s.AMOUNT) amount       
from  STOCK s left outer join NEW_STOCK n 
      on s.ID_DATE = n.ID_DATE
         and s.ID_SELLER = n.ID_SELLER
         and s.ID_INVOICE = n.ID_INVOICE
         and s.ID_DOC = n.ID_DOC
where s.ID_DATE = 1
  and s.ID_SELLER = 'SELL1';

Answer 2

SELECT * FROM (
    SELECT * FROM new_stock
    UNION ALL
    SELECT * FROM stock
    WHERE (ID_DATE,ID_SELLER,ID_INVOICE,ID_DOC) NOT IN 
     (SELECT ID_DATE,ID_SELLER,ID_INVOICE,ID_DOC FROM new_stock)
)
WHERE ID_DATE = 1 
   AND ID_SELLER = 'SELL1';

Answer 3

以下内容适用于此：

SELECT s.AMOUNT, s.ID_DATE, s.ID_SELLER, s.ID_INVOICE    
FROM STOCK s
LEFT JOIN NEW_STOCK ns 
   ON s.ID_DATE = ns.ID_DATE 
   AND s.ID_SELLER = ns.ID_SELLER 
   AND s.ID_INVOICE = ns.ID_INVOICE
WHERE s.ID_DATE = 1      
  AND s.ID_SELLER = 'SELL1'
  AND ns.ID_DATE IS NULL
UNION
SELECT AMOUNT, ID_DATE, ID_SELLER, ID_INVOICE    
FROM NEW_STOCK    
WHERE ID_DATE = 1
  AND ID_SELLER = 'SELL1';

从使用NEW_STOCK表的结果设置的LEFT JOIN和UNION中排除匹配的行。

Answer 4

SELECT COALESCE(NS.AMOUNT, S.AMOUNT) AMOUNT, 
       S.ID_DATE, 
       S.ID_SELLER, 
       S.ID_INVOICE
  FROM STOCK S 
  LEFT JOIN NEW_STOCK NS ON S.ID_DATE = NS.ID_DATE
                        AND S.ID_SELLER = NS.ID_SELLER
                        AND S.ID_INVOICE = NS.ID_INVOICE
                        AND S.ID_DOC = NS.ID_DOC 
 WHERE S.ID_DATE = 1
   AND S.ID_SELLER = 'SELL1'

如何从Oracle 10中的两个表连接结果

4 个答案: