Re: Ask About SQL

In response to Otniel Michael :
> Hi All.
>
> Can help to create sql queries for this data :
>
> tabel A
> field1, field2, field3
> x1,     y1,     5
> x1,     y2,     1
> x2,     y1,     2
> x2,     y3,     4
> x1,     y3,     4
>
> I want to get 2 record with the max value at field3 for each kombination of
> field1 :
>
> tabel B
> field1, field2, field3
> x1,     y1,     5
> x1,     y3,     4
> x2,     y3,     4
> x2,     y1,     2
>
> Anyone have an ideas?

Works since 8.4:

test=*# select * from table_a ;
field1 | field2 | field3
--------+--------+--------
x1 | y1 | 5
x1 | y2 | 1
x2 | y1 | 2
x2 | y3 | 4
x1 | y3 | 4
(5 rows)

test=*# select field1, field2, field3 from (select field1, field2,
field3, row_number() over(partition by field1 order by field3 desc) from
table_a order by field1, field3) foo where row_number < 3 order by
field1, field2;
field1 | field2 | field3
--------+--------+--------
x1 | y1 | 5
x1 | y3 | 4
x2 | y1 | 2
x2 | y3 | 4
(4 rows)

Regards, Andreas
--
Andreas Kretschmer
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