Re: How to count elements in an array?

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Re: How to count elements in an array?

От:
Josh Berkus <josh@agliodbs.com>
Дата:
Grant,
The only way I know to enumarate arrays is procedural.  This is a good
reason to stay away from arrays except in buffer and temporary tables
(aside from the fact that array columns violate the relational principle
of atomicity).
The following sample procedure, paraphrased from Bruce Momjian's book
(which you should buy, hint, hint) illustrates enumerating an array of
INT4 values:

CREATE FUNCTION count_array ( INT4[] ) RETURNS INT2
AS '
DECLARE array_loop INT2;array_col ALIAS FOR $1;
BEGINarray_loop := 1;WHILE array_col[array_loop]  LOOP	array_loop = array_loop + 1;END LOOP;array_loop := array_loop - 1RETURN array_loop;
END;'
LANGUAGE 'plpgsql';

				-Josh
-- 
______AGLIO DATABASE SOLUTIONS___________________________                                       Josh Berkus  Complete information technology      josh@agliodbs.com   and data management solutions       (415) 565-7293  for law firms, small businesses       fax  621-2533   and non-profit organizations.       San Francisco

How to count elements in an array?

От:
Grant <grant@conprojan.com.au>
Дата:
How can I obtain a count (number) of elements in a text array? Thanks.

test=# \d array                             Table "array" Attribute   |  Type   |                    Modifier
--------------+---------+------------------------------------------------id           | integer | not null default nextval('array_id_seq'::text)to_group_ids | text[]  |
Index: array_pkey

test=#

--- EXAMPLE SELECT ---

test=# select to_group_ids[1] from array where id=1;to_group_ids
--------------1
(1 row)

test=#
FAQ