RE: SQL - select the record with the highest count value within afield

["Lim Hock-Chai" <Lim.Hock-Chai@xxxxxxxxxxxxxxx>]

I haven't try it but I think it would result in:
AAA      A12       D1          5
BBB      B17       DC          5 (incorrect result, this record does not
exist in original file)

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of
AGlauser@xxxxxxxxxxxx
Sent: Friday, September 22, 2006 3:13 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: SQL - select the record with the highest count value within
afield

> Forgive me.  Can I make it a bit more challenging by adding one more 
> field to the data?
> Example:
> Data:
> FIELD1   FIELD2    FIELD3    COUNTFIELD
> AAA      A12       D1          5
> AAA      A13       D5          2
> AAA      A14       D2          1
> BBB      B17       CC          5
> BBB      B13       DC          5
> BBB      B15       D1          1
>
> Result needed (Assuming FIELD1 is the field where the highest 
> COUNTFIELD need to select from)
> FIELD1   FIELD2    FIELD3   COUNTFIELD
> AAA      A12       D1          5
> BBB      B17       CC          5
>
> Or
>
> FIELD1   FIELD2    FIELD3   COUNTFIELD
> AAA      A12       D1          5
> BBB      B13       DC          5

I think to add a third field as you mentioned, you would just need to
extend Birgitta's example with one more Common Table Expression:

     c as (Select  b.Field1, b.maxfield2, Maxcount, Max(Field3) as
MaxField3
              from b join MyTable x
                on b.Field1 = x.Field1 and b.maxfield2=x.field2 and
a.CountField = MaxCount) select y.* from MyTable y join c 
     on y.Field1 = c.Field1 and y.Field2 = c.MaxField2 and y.field3 =
c.MaxField 3 and CountField = MaxCount

I think a simliar technique would work for n fields, but as some point
this becomes really ugly and you probably want to consider using record
I/O and SETGT.

HTH,
Adam





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