From: Leif B. Kristensen <leif@solumslekt.org>
To: pgsql-sql@postgresql.org
Subject: Multiple return values and assignment
Date: Sat, 25 Apr 2009 13:06:44 +0200
Message-ID: <200904251306.44880.leif@solumslekt.org> (raw)
I've got a function that returns both an integer and a string as a
user-defined composite type int_text:
-- CREATE TYPE int_text AS (number INTEGER, string TEXT);
Basically, the function does some heuristics to extract a sort order
number from a text, and conditionally modify the text:
CREATE OR REPLACE FUNCTION get_sort(INTEGER, INTEGER, TEXT)
RETURNS int_text AS $$
-- parse text to infer sort order; factored out of add_source() below
-- because the functionality needs to be accessed directly from PHP as
-- well, and this approach eliminates previous duplication of code.
-- CREATE TYPE int_text AS (number INTEGER, string TEXT)
DECLARE
par_id INTEGER = $1;
srt INTEGER = $2;
txt TEXT = $3;
sort_text int_text;
BEGIN
-- default condition: if nothing is modified, return input values
sort_text.number := srt;
sort_text.string := txt;
-- 1) use page number for sort order
-- (low priority, may be overridden)
IF srt = 1 THEN -- don't apply this rule unless sort = default
IF txt SIMILAR TO E'%side \\d+%' THEN
-- use page number as sort order
SELECT SUBSTR(SUBSTRING(txt, E'side \\d+'), 5,
LENGTH(SUBSTRING(txt, E'side \\d+')) -4)::INTEGER
INTO sort_text.number;
END IF;
END IF;
-- 2) use ^#(\d+) for sort order
IF txt SIMILAR TO E'#\\d+%' THEN
SELECT SUBSTR(SUBSTRING(txt, E'#\\d+'), 2,
LENGTH(SUBSTRING(txt, E'#\\d+')) -1)::INTEGER
INTO sort_text.number;
-- strip #number from text
sort_text.string := REGEXP_REPLACE(txt, E'^#\\d+ ', '');
END IF;
-- 3) increment from max(sort_order) of source group
IF txt LIKE '++ %' THEN
SELECT MAX(sort_order) + 1
FROM sources
WHERE get_source_gp(source_id) =
(SELECT parent_id FROM sources WHERE source_id = par_id)
INTO sort_text.number;
-- strip symbol from text
sort_text.string := REPLACE(txt, '++ ', '');
END IF;
RETURN sort_text;
END
$$ LANGUAGE plpgsql STABLE;
To use the two values in an other function where I've declared a
variable sort_text of type int_text, I do like this:
SELECT number, string FROM get_sort(par_id, srt, txt) INTO sort_text;
srt := sort_text.number;
txt := sort_text.string;
But I feel it's a little awkward. Is there a more elegant way to do it?
I can't run the get_sort() function twice, because it modifies its
input values.
--
Leif Biberg Kristensen | Registered Linux User #338009
Me And My Database: http://solumslekt.org/blog/
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To: pgsql-sql@postgresql.org
Cc: leif@solumslekt.org
Subject: Re: Multiple return values and assignment
In-Reply-To: <200904251306.44880.leif@solumslekt.org>
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