Question

我想仅从内连接返回第一行。我有两张桌子：

TABLE_D和TABLE_E中的行可以具有相同的创建日期，因此我首先获得MAX（creationdate），然后从该集合获得MAX（id）。这是我的完整查询：



SELECT
a.id as A_ID,
b.id as B_ID,
c.id as C_ID,
d.id as D_ID,
e.id as E_ID,
d.CREATIONDATE,
a.REFNUMBER,
a.DATECREATED,
a.INFO,
e.COST,
FROM 
TABLE_A a
INNER JOIN TABLE_B b ON (b.id = a.id)
INNER JOIN TABLE_C c ON (c.id = b.id)
INNER JOIN TABLE_D d ON
(
   c.i =
   (
      select
      d.id
      FROM TABLE_D
      WHERE TABLE_D.id = c.id
      AND TABLE_D.id =
      (
         select
         max(id)
         from TABLE_D t1
         where c_id = c.id
         and CREATIONDATE =
         (
            select
            max(CREATIONDATE)
            from TABLE_D t2
            where t2.c_id = t1.c_id
         )
      )
   ) 
)

INNER JOIN TABLE_E e ON
(
   d.i =
   (
      select
      e.d_id
      from TABLE_E
      where d_id = d.id
      AND id =
      (
         select
         max(id)
         from e t1
         where e.d_id = d.id
         and CREATIONDATE =
         (
            select
            max(CREATIONDATE)
            from TABLE_E t2
            where t2.d_id = t1.d_id
         )
      )
   )
)

我的子查询获取具有最大创建日期的所有行，并且当我自己调用它时，max id工作正常但是当我将它添加到INNER JOIN（参见上文）时，我为每个匹配的行获取一行在表D和表E中。我想要的是每个TABLE_A.id一行，仅显示与TABLE_C关联的TABLE_D中的最新行以及与TABLE_D关联的TABLE_E中的最新行。

例如，我的结果集中的id现在看起来像这样：



--------------------------------------------------------------------------
A_ID            B_ID            C_ID            D_ID            E_ID
--------------------------------------------------------------------------
1               101             201             301             401
1               101             201             301             402    
1               101             201             301             403    
1               101             201             302             404
1               101             201             302             405    
1               101             201             302             406

我需要的是这个：



--------------------------------------------------------------------------
A_ID            B_ID            C_ID            D_ID            E_ID
--------------------------------------------------------------------------
1               101             201             302             406

提前感谢您的帮助。

Answer 1

使用oracle11g

中提供的分析函数ROW_NUMBER（）

SELECT *
FROM 
(
SELECT
    a.id as A_ID,b.id as B_ID,c.id as C_ID,d.id as D_ID,e.id as E_ID,
    d.CREATIONDATE,a.REFNUMBER,a.DATECREATED,a.INFO,e.COST,
    row_number() over (
        partition by a.id, b.id, c.id
        order by d.CREATIONDATE DESC, d.id desc, e.CREATIONDATE DESC, e.id desc) RN
FROM TABLE_A a
INNER JOIN TABLE_B b ON (b.id = a.id)
INNER JOIN TABLE_C c ON (c.id = b.id)
INNER JOIN TABLE_D d ON d.c_id = c.id
INNER JOIN TABLE_E e ON e.d_id = d.id
) N
WHERE RN = 1

确保PARTITION和ORDER BY子句正确

partition by a.id, b.id, c.id
    => start numbering from 1 again when any one of these changes
order by d.CREATIONDATE DESC, d.id desc, e.CREATIONDATE DESC, e.id desc)
    => number the rows in this order

Answer 2

我要做的是将内部查询移动到select子句。我将在过滤时保持直接映射

SELECT
a.id as A_ID,
b.id as B_ID,
c.id as C_ID,
(select max(d.id) from d where d.id =c.id) as d_id)
FROM 
TABLE_A a
INNER JOIN TABLE_B b ON (b.id = a.id)
INNER JOIN TABLE_C c ON (c.id = b.id)

Answer 3

您可以在子查询中插入查询并使用WHERE ROWNUM＆lt; 2过滤器。

SELECT * FROM
(/* Your SQL */)
WHERE ROWNUM < 2

Answer 4

这可能对你有用吗？

SELECT TOP 1
a.id as A_ID,
b.id as B_ID,
c.id as C_ID,
d.id as D_ID,
e.id as E_ID,
d.CREATIONDATE,
a.REFNUMBER,
a.DATECREATED,
a.INFO,
e.COST,
FROM 
TABLE_A a
INNER JOIN TABLE_B b ON (b.id = a.id)
INNER JOIN TABLE_C c ON (c.id = b.id)
INNER JOIN TABLE_D d ON (c.i = d.id)
INNER JOIN TABLE_E e ON ( d.i = e.id )
ORDER BY d.creationdate DESC, e.creationdate DESC

在INNER JOIN上返回一行

4 个答案: