ivan marchesini wrote:
Dear users....
It's a simple problem I think (and I hope :-)
I have a table like this:
A|B|C
1|2|20
1|3|10
1|4|21
2|3|12
2|4|22
3|4|23
where the first two column are a combination without repetition (with
k=2) of the numbers 1,2,3,4
for each pair I have a value in the column C.
I would want a select that can extract these records:
1|3|10
2|3|12
3|4|23
i.e. the select must look into the A field first and:
-select all records where A=1,
-find, into this selection, the record where there's the minimum value
of the field C
-print all the fields for this record.
then
-select all records where A=2
-find, into this selection, the record where there's the minimum value
of the field C
-print all the fields of this record.
and so on...
using
SELECT a,MIN(c) FROM table GROUP BY a
is a partial solution because I can't see the value of B
and I obtain:
1|10
2|12
3|23
How can I do for plotting also the value of B???
Thank you very much
Ivan
Maybe you could try
Select distinct on (a,b) a,b,c from(select * from table order by A,C)
The distinct on construct is a postgreSql-ism
Cordialement
--
Patrick
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