At the moment I have two probable solutions, the first makes use of
cursors and requires looping though each record, the other a
not-so-elegant solution (and may be unfavourable for large datasets)
makes use of arrays and the EXECUTE command (in plpgsql).
The second solution is as follows.
DROP table imaginary;
CREATE temp table imaginary(id INTEGER NOT NULL, some_field FLOAT
NULL,primary key(id));
INSERT INTO imaginary(id,some_field)VALUES(1,0.333);INSERT INTO
imaginary(id,some_field)VALUES(2,0.667);INSERT INTO
imaginary(id,some_field)VALUES(3,0.4);INSERT INTO
imaginary(id,some_field)VALUES(4,null);
SELECT array_to_string(ARRAY(SELECT a.some_field FROM imaginary a),'*');
--within plpgsql execute the following
EXECUTE 'SELECT '||SELECT array_to_string(ARRAY(SELECT a.some_field FROM
imaginary a),'*') INTO _my_aggregated_product;
Allan.
Allan Kamau wrote:
Hi
I would like to calculate a product of a field's values of a relation,
this function may multiply each value and give the result as a single
float number.
For example:
CREATE table imaginary(id INTEGER NOT NULL, some_field FLOAT
NULL,primary key(id));
INSERT INTO imarginary(1,0.333);INSERT INTO imarginary(2,0.667);INSERT
INTO imarginary(3,0.4);
SELECT prod(some_field) FROM imarginary;
would give 0.0888444 (which is 0.333*0.667*0.4)
Is there an already existing function that does this.
Allan.
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