Re: PL/pgSQL 'i = i + 1' Syntax

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: David Wheeler <david(at)kineticode(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PL/pgSQL 'i = i + 1' Syntax
Date: 2006-05-16 23:30:35
Message-ID: 446A609B.9040700@dunslane.net
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David Wheeler wrote:
> Hellow PostgreSQL hackers,
>
> Quick question. Why does the 'i = i + 1' syntax work in this PL/pgSQL
> function?
>
> try=# CREATE OR REPLACE FUNCTION inc_by_two(
> try(# upfrom int,
> try(# upto int
> try(# ) RETURNS SETOF INT AS $$
> try$# BEGIN
> try$# FOR i IN upfrom..upto LOOP
> try$# RETURN NEXT i;
> try$# i = i + 1;
> try$# END LOOP;
> try$# END;
> try$# $$ LANGUAGE 'plpgsql';
> CREATE FUNCTION
> try=# select * from inc_by_two(1,10);
> inc_by_two
> ------------
> 1
> 3
> 5
> 7
> 9
> (5 rows)
>
> Someone posted a PL/pgSQL function in my blog with this syntax, which
> is how I know about it, but I couldn't find it documented anywhere. Is
> it a special exception for loop variables, perhaps?
>

It ought to be illegal to modify the loop control variable anyway,
IMNSHO - it certainly is in Ada, the distant antecedent of pl/pgsql.

cheers

andrew

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