Message-ID: <4149C90D.60806@lnl.infn.it>
Date: Thu, 16 Sep 2004 19:10:37 +0200
From: Sergio Fantinel <sergio.fantinel@lnl.infn.it>
Reply-To: sergio.fantinel@lnl.infn.it
Organization: INFN-LNL :: Nuclear Phisic National Institute - Legnaro National
	Laboratory
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To: pgsql-sql@postgresql.org
Subject: PL/pgSQL multidimension (matrix) array in function
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I found how to use, inside a PL/pgSQL function, a two-dimensions array (matrix).
There is a limitation: the number of the 'columns' of the matrix is fixed at 
declaration time (in DECLARE section) and you need to manually initialize all 
the elements in the first 'row' of the matrix.

The number of rows is unlimited and can be sized at runtime.

Here is the code that can help you.

If someone know how to manage an NxN array without limitations, please replay 
to this thread.

I'm using PostgreSQL 7.4.1 on RH7.3

Cheers
	Sergio

CREATE OR REPLACE FUNCTION "testarray" (integer) RETURNS SETOF integer AS'
DECLARE
        n alias for $1;	-- number of rows is passed as argument
        i INTEGER;
        j integer;
        k INTEGER := 3;            -- matrix columns number
        b integer[] := array[0,0,0];    -- need it to initialize the matrix!!
        a integer[][] := array[[0,0,0]]; -- need it to initialize the matrix!!
begin

      for i in 1..n loop		-- the i loop can start obviously from 2 (the first 
row is already present...) but for our purpose here we use 1
           a := array_cat(a,b);
           for j in 1..k loop
               a[i][j] := i*j;
           end loop;
      end loop;
      for i in 1..n loop

          return next null;
          return next i;        -- need it to format in some way the output :)
          return next null;

          for j in 1..k loop
              return next a[i][j];
          end loop;

      end loop;
      return;
end
'LANGUAGE 'plpgsql';


here is the output:

=> select * from testarray(8);
  testarray
-----------

          1

          1
          2
          3

          2

          2
          4
          6

          3

          3
          6
          9

          4

          4
          8
         12

          5

          5
         10
         15

          6

          6
         12
         18

          7

          7
         14
         21

          8

          8
         16
         24
(48 rows)


-- 
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Sergio Fantinel                           EGEE Project
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INFN - Lab. Naz. di Legnaro               phone: +39 049 8068 489
viale dell'Università n. 2,
35020 Legnaro (PD) ITALY                  sergio.fantinel@lnl.infn.it
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