需要帮助在仅需要 return 最新值的 JOIN 查询之上创建视图

Question

我的 SQL 查询需要帮助我有两个表需要使用 LEFT OUTER JOIN 连接，然后我需要在该特定视图上创建数据库视图。如果我运行查询连接以查找名称 A，我需要获取 A 的最新品牌 "AP"。 Table1

ID     name     address
-----------------------  
1      A         ATL
2      B         ATL

TABLE 2

ID     PER_ID    brand      DATEE
--------------------------------------------
1      1         MS           5/19/17:1:00pm
2      1         XB           5/19/17:1:05pm
3      1         AP           5/19/17:2:00pm
4      2         RO           5/19/17:3:00pm
5      2         WE           5/19/17:4:00pm

我尝试查询 returns 正确的结果，但是当我尝试在连接之上构建数据库视图时遇到问题 1。我尝试了查询 b，但是当我在 oracle sql 开发人员中查询我的视图时，我仍然得到所有结果，但不是最新的。

查询一个：

SELECT * from table_1
left outer join table_2 on table_1.ID = Table_2.PER_ID
AND table_2.DATE = (SELECT MAX(DATE) from table_2 z where z.PER_ID = table_2.PER_ID)

问题 1

Error report -
ORA-01799: a column may not be outer-joined to a subquery
01799. 00000 -  "a column may not be outer-joined to a subquery"
*Cause:    <expression>(+) <relop> (<subquery>) is not allowed.
*Action:   Either remove the (+) or make a view out of the subquery.
           In V6 and before, the (+) was just ignored in this case.

查询 2：

SELECT * from table_1
    left outer join(SELECT PER_ID,brand, max(DATEE) from table_2 group by brand,PER_ID) t2 on table_1.ID = t2.PER_ID

Answer 1

使用row_number():

select t1.id, t1.name, t1.address, t2.id as t2_id, t2.brand, t2.datee
from table_1 t1 left outer join
     (select t2.*,
             row_number() over (partition by per_id order by date desc) as seqnum
      from table_2 t2
     ) t2
     on t1.ID = t2.PER_ID and t2.seqnum = 1;

定义视图时，您应该养成明确列出列的习惯。

需要帮助在仅需要 return 最新值的 JOIN 查询之上创建视图

Need help creating a view on top of a JOIN query that needs to return only the latest value

oracle

join

left-join

oracle12c