[Dbix-class] selecting records with no links-to

[Wolfgang Kinkeldei]

Hi,

Am 14.06.2013 um 13:31 schrieb Dave Howorth:

> My brain is feeling fried and is failing to solve a simple puzzle.
> 
> Using the standard table 'artist' which has a primary key 'artistid'.
> 
> And the other table 'cd' that has a link to artists, via a foreign key
> 'artist'. There may be more than one CD associated with a single artistid.
> 
> I want a resultset containing all artists which have NO associated CD.
> 
> What's the appropriate way to select this resultset?

one way would be to shrink your resultset with '-not_in'. However, "NOT IN" in SQL is sometimes very inefficient.

my $artists_with_cd =
    $schema->resultset('CD')->get_column('artist')->as_query;

my @artists_without_cd =
    $schema->resultset('Artist')->search( { artistid => { -not_in => $artists_with_cd } } )->all;


Best,

Wolfgang Kinkeldei

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