Question

I need the result for every combination of (from_id, to_id) which has the minimun value and the loop matching a criteria.

因此,我基本上需要具有微型价值的通道。 e. 例如,从A到B,需要微型价值和补贴。

The table has the following fields:

value     from_id   to_id     loop_id
-------------------------------------

2.3         A         B          2

0.1         A         C          2

2.1         A         B          4

5.4         A         C          4

结果是:

value     from_id   to_id     loop_id
-------------------------------------

2.1         A         B          4

0.1         A         C          2

I have tried with the following:

SELECT t.value, t.from_id, t.to_id,t.loop_id
FROM myresults t 
INNER JOIN (
     SELECT min(m.value), m.from_id, m.to_id, m.loop_id
     FROM myresults m where m.loop_id % 2 = 0
     GROUP BY m.from_id, m.to_id, m.loop_id
) x
   ON  (x.from_id = t.from_id and x.to_id=t.to_id and x.loop_id=t.loop_id )
   AND x.from_id = t.from_id and x.to_id=t.to_id and x.loop_id=t.loop_id

But it is returning all the loops. Thanks in advance!

Answer 1

我理解这个问题,这将发挥作用:

SELECT  t.value, t.from_id, t.to_id, t.loop_id
FROM    MyResults t
        INNER JOIN
        (   SELECT  From_ID, To_ID, MIN(Value) [Value]
            FROM    MyResults
            WHERE   Loop_ID % 2 = 0
            GROUP BY From_ID, To_ID
        ) MinT
            ON MinT.From_ID = t.From_ID
            AND MinT.To_ID = t.To_ID
            AND MinT.Value = t.Value

然而,如果您对从ID到ID的组合具有重复价值,例如:

value     from_id   to_id     loop_id
-------------------------------------

0.1         A         B          2

0.1         A         B          4

这将使两行都返回。

如果你在2005年或以后使用Kall-Server,你希望像上文所述的重复浏览器能够使用:

SELECT  Value, From_ID, To_ID, Loop_ID
FROM    (   SELECT  *, MIN(Value) OVER(PARTITION BY From_ID, To_ID) [MinValue]
            FROM    MyResults
        ) t
WHERE   Value = MinValue

如果你不希望重复行,你可以这样做:

SELECT  Value, From_ID, To_ID, Loop_ID
FROM    (   SELECT  *, ROW_NUMBER() OVER(PARTITION BY From_ID, To_ID ORDER BY Value, Loop_ID) [RowNumber]
            FROM    MyResults
        ) t
WHERE   RowNumber = 1

Answer 2

你们怎么做更简单吗?

SELECT
  from_id,
  to_id,
  MIN(value)
FROM
  myresults
WHERE
  loop_id % 2 = 0
GROUP BY
  from_id,
  to_id

或者也许我会误解这个问题。

EDIT: 包括住宿

SELECT
  m2.from_id,
  m2.to_id,
  m2.value,
  m2.loop_id
FROM
  myresults m2 INNER JOIN
    (SELECT
      m1.from_id,
      m1.to_id,
      MIN(m1.value)
    FROM
      myresults m1
    WHERE
      m1.loop_id % 2 = 0
    GROUP BY
      m1.from_id,
      m1.to_id) minset
  ON
        m2.from_id = minset.from_id
    AND m2.to_id = minset.to_id
    AND m2.value = minset.value

友情链接