RE: Window ?

Thanks David, Gerardo,

I had a look to crosstab functions but wasn't able to make them work, documentation is not precise enough to me, I would appreciate if someone has a working sample. Based on your suggestion, I will try again anyway. The main difficulty is that I have not only one column but half a dozen taht I would like to appear

road 1 colA colB colC colD colE ColF colA colB colC colD colE ColF colA colB colC colD colE ColF ...

road 2 colA colB...

for each road.

Olivier

De : David G. Johnston [mailto:david(dot)g(dot)johnston(at)gmail(dot)com]
Envoyé : mercredi 13 juin 2018 16:55
À : Olivier Leprêtre
Cc : pgsql-sql
Objet : Re: Window ?

On Wed, Jun 13, 2018 at 7:33 AM, Olivier Leprêtre <o(dot)lepretre(at)gmail(dot)com> wrote:

I want to convert records into lines,

1 att1 att2 att3 att4

2 att5 att6 ...

​I would recommend either an actual array (array_agg function) or a structured string (string_agg function)

SELECT road, array_agg(colA ORDER BY seg)

FROM tbl

GROUP BY road;

Otherwise you will need a output 31 columns with unused columns holding null. You can do that brute-force or you can leverage the tablefunc extension's crosstab function.

https://www.postgresql.org/docs/10/static/tablefunc.html

David J.

​

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