How to count the number of items in an Array?

Andre Lopes <lopes80andre@gmail.com> wrote:

Hi,

I have googled, but I can't find how to count the number of items in an Array
in Plpgsql.

Someone can give me a clue on that?

Sure, you can use array_upper() - array_lower():

Zeit: 0,205 ms
test=*# select array_upper(array[1,2,3],1) - array_lower(array[1,2,3],1);
?column?
----------
2
(1 Zeile)

or:

test=*# select array_upper(array[1,2,3],1) - array_lower(array[1,2,3],1) + 1;
?column?
----------
3
(1 Zeile)

Or, if your array starts with the first element, simple:

test=*# select array_upper(array[1,2,3,NULL,5],1);
array_upper
-------------
5
(1 Zeile)

Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknown)
Kaufbach, Saxony, Germany, Europe. N 51.05082�, E 13.56889�

Hi,

Thanks for the reply.

My problem is that I can't have the array with all items. I need to read
from a table and store in an Array the values.

I have this:

[code]
CREATE OR REPLACE FUNCTION "public"."apr_update_newsletter_distritos"
("pEMAIL" varchar, "pID_WEBSITE_RECOLHA" varchar) RETURNS void AS
$body$
DECLARE
pEMAIL alias for $1; -- vai ser preciso
pID_WEBSITE_RECOLHA alias for $2; -- vai ser preciso
vDISTRITOS_NA_TABELA varchar[];
vDISTRITOS_NA_TABELA_CONST varchar[];
vd integer;
vas varchar;
BEGIN
-- ### Vou gravar num array os registos da chave em q se vai mexer
-- vou entao passar os registos para o array vDISTRITOS_NA_TABELA
FOR vDISTRITOS_NA_TABELA IN
SELECT array[id_distrito] FROM am_newsletter_distritos
WHERE email = pEMAIL and id_website_recolha = pID_WEBSITE_RECOLHA
LOOP
RAISE NOTICE 'value: %', vDISTRITOS_NA_TABELA;
END LOOP;

-- array 2 string
select array_to_string(vDISTRITOS_NA_TABELA, ',') into vas;
RAISE NOTICE 'string with items of array: %', vas;

-- Vou contar o número dos registos do array
-- select array_upper(vDISTRITOS_NA_TABELA, 1) into vd;
-- RAISE NOTICE 'num array: %', vd;
END;
$body$
LANGUAGE 'plpgsql' VOLATILE CALLED ON NULL INPUT SECURITY INVOKER;
[/code]
This select returns me 4 values:
[code]
SELECT array[id_distrito] FROM am_newsletter_distritos
WHERE email = pEMAIL and id_website_recolha = pID_WEBSITE_RECOLHA
[/code]

The values are '11, 12,16, 16'. I haven't found a way to store this as an
array to the variable vDISTRITOS_NA_TABELA. Someone can give me a clue on
how to do that?

Best Regards,

On Sun, Feb 21, 2010 at 8:38 AM, Andreas Kretschmer <
akretschmer@spamfence.net> wrote:

Andre Lopes <lopes80andre@gmail.com> wrote:

Hi,

Thanks for the reply.

My problem is that I can't have the array with all items. I need to read from a
table and store in an Array the values.

Not sure if i understand you, but how about:

test=*# select * from foo;
a
---
1
3
5
7
(4 Zeilen)

Zeit: 0,203 ms
test=*# select array_agg(a) from foo;
array_agg
-----------
{1,3,5,7}
(1 Zeile)

The function returns a column as an array.

Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknown)
Kaufbach, Saxony, Germany, Europe. N 51.05082�, E 13.56889�

One more time, thanks for the reply. I'am using postgre 8.3. I think I don't
have the array_agg(), there is another way of doing it?

Best Regards,

On Sun, Feb 21, 2010 at 2:46 PM, Andreas Kretschmer <
akretschmer@spamfence.net> wrote:

Andre Lopes <lopes80andre@gmail.com> wrote:

One more time, thanks for the reply. I'am using postgre 8.3. I think I don't
have the array_agg(), there is another way of doing it?

Sure.

The doc contains an example for a user-defined aggregate-function:
http://www.postgresql.org/docs/8.4/interactive/xaggr.html

It works with versions prior 8.4.

test=*# CREATE AGGREGATE array_accum (anyelement)
test-# (
test(# sfunc = array_append,
test(# stype = anyarray,
test(# initcond = '{}'
test(# );
CREATE AGGREGATE
Zeit: 44,645 ms
test=*# select array_accum(a) from foo;
array_accum
-------------
{1,3,5,7}
(1 Zeile)

Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknown)
Kaufbach, Saxony, Germany, Europe. N 51.05082�, E 13.56889�

Hi,

Thanks for the reply.

I have done it in this way:

[code]
FOR vDISTRITOS_NA_TABELA IN
SELECT array[id_distrito] FROM am_newsletter_distritos
WHERE email = pEMAIL and id_website_recolha = pID_WEBSITE_RECOLHA
LOOP
vDISTRITOS_NA_TABELA_CONST := vDISTRITOS_NA_TABELA_CONST ||
vDISTRITOS_NA_TABELA;
END LOOP;
[/code]

Best Regards,

On Sun, Feb 21, 2010 at 3:25 PM, Andreas Kretschmer <
akretschmer@spamfence.net> wrote: