From: | Mark Dilger <pgsql(at)markdilger(dot)com> |
---|---|
To: | David Wheeler <david(at)kineticode(dot)com> |
Subject: | Re: PL/pgSQL 'i = i + 1' Syntax |
Date: | 2006-05-16 23:37:19 |
Message-ID: | 446A622F.10209@markdilger.com |
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Thread: | |
Lists: | pgsql-hackers |
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?
>
> Thanks,
>
> David
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster
>
The syntax for assignment is:
i := i + 1
what you are doing is merely comparison. Since you are not using the results of
the comparison, it is a no-op.
mark
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