Re: Converting each item in array to a query result row

----- Original Message -----
From: "Postgres User" <postgres.developer@gmail.com>
To: "pgsql-general" <pgsql-general@postgresql.org>
Sent: Friday, May 29, 2009 12:21:11 AM GMT -08:00 Tijuana / Baja California
Subject: [GENERAL] Converting each item in array to a query result row

Hi,

I'd writing a query against a function (pg_proc) that contains 2
fields of an array type.  Ideally, I'd like to select 1 row from the
table, but return a query row for each item in the array.

For example, if one row contains the array {"a", "b", "c"}
I'd like the query to return 3 rows, one for each of these elements.

Any idea if this is possible?


Not sure exactly what you want, but this should get you in the ball park

SELECT f.my_field[i] AS value, 
(array['I am one','I am two','I am three'])[i] AS description
FROM my_func(foo) f
JOIN generate_series(1,3) i ON 1=1

Postgres 8.4 will has an unpack() function to convert an array to a set. Pavel has a write up about doing this in 8.3 and lower here:

http://www.postgres.cz/index.php/PostgreSQL_SQL_Tricks#Array_to_table

I've got some examples of pulling data ouf of arrays here:

http://scottrbailey.wordpress.com/2009/05/20/etl-with-postgres-arrays/