Question

我正在尝试将数据（产品，时间戳）插入表格A，B和表格xyz中。 C使用主键作为PRODUCT。这三个表都有一个timestamp列和其他列。我想插入包含产品的行和这三个表（A，B＆amp; C）的最大时间戳。

Answer 1

如果表xyz中已存在产品，则不指定要发生的情况，因此假设它不存在，您可以使用如下查询：

Insert into XYZ(Product, Timestamp)
Select Product, max(timestamp)
  from (select product, timestamp from a union all
        select product, timestamp from b union all
        select product, timestamp from c)
 group by product

Answer 2

您可以尝试以下方法：

INSERT INTO xyz
  ( product, timestamp )
SELECT MAX(product) KEEP ( DENSE_RANK FIRST ORDER BY timestamp DESC ) AS product
     , MAX(timestamp)
  FROM a
 UNION ALL
SELECT MAX(product) KEEP ( DENSE_RANK FIRST ORDER BY timestamp DESC ) AS product
     , MAX(timestamp)
  FROM b
 UNION ALL
SELECT MAX(product) KEEP ( DENSE_RANK FIRST ORDER BY timestamp DESC ) AS product
     , MAX(timestamp)
  FROM c;

希望这有帮助。

Answer 3

根据Sentine的评论

更新：

试试这个（语法未经验证）：

INSERT INTO xyz (product , timestamp) 
 (
    SELECT product , MAX(A.timestamp) 
      FROM A
    UNION
    SELECT product , MAX(B.timestamp) 
      FROM B
    UNION
    SELECT product , MAX(C.timestamp) 
      FROM C
) ;

Oracle PL / SQL - 根据列的最大值插入值

3 个答案: