How to count pairs? - Mailing list pgsql-general

From Andrej Kastrin
Subject How to count pairs?
Date
Msg-id 466BE367.9020500@siol.net
Whole thread Raw
Responses Re: How to count pairs?  ("A. Kretschmer" <andreas.kretschmer@schollglas.com>)
List pgsql-general
Dear all,

I need to count all pairs of instances which occure under given ID
number, e.g.:

ID word
-------------
1   car
1   fruit
2   car
2   fruit
2   vegetable
3   car
3   vegetable

And the output should be simillar to:

car fruit 2
car vegetable 2
fruit vegetable 1

Any suggestion how to do that in PgSQL? Thanks in advance for any pointers.

Cheers, Andrej

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