List:General Discussion« Previous MessageNext Message »
From:barney Date:March 25 2006 11:47pm
Subject:Re: Find records not in many-to-many table?
View as plain text  
Thanks, Stefan,

But that only works if both tables have the same field name, doesn't it?  If I use
select FileKey from dl_files left join dl_merges using (FileID) where FileID is null
MySQL returns
Unknown column 'articles.dl_files.FileID' in 'on clause'.

Correct me if I'm wrong, but wouldn't I have to modify the column name in one of the
tables in order for that to work?  Or is there a syntax in the join lexicon that I can
use to alias one of the column names within the query?  I can't modify the existing table
structure(s).

Apologies if I'm being dense.

Make a good day ...
                                 ... barn

> Use

> select first_table.id from first_table left join second_table using (id) where
> second_table.id is null

> Stefan


> Am Saturday 25 March 2006 19:10 schrieb barney:
> > Folk,
> >
> > This may be off-base for this list, but I've run out of places to look,
> > sorry.  I can't seem to find this anywhere, although I'm certain I've seen
> > it before.
> >
> > How can I identify all the records in a table that are not referenced in a
> > many-to-many table?
> >
> > I have a [unique] table of files and a [unique] table of attributes.  These
> > are linked in a merge table which is many-to-many.  I need to find all
> > items in the file table that are not referenced in the merge table in order
> > to add appropriate attributes for those records.  The attribute list is
> > 26-30 records and the file table is currently about 3,200 records, which
> > could make for a merge table of 96,000 records.
> >
> > I tried using an IN statement against a sub-select of unique file ids in
> > the merge table, but either that will not work or I did not craft it
> > properly  The query hit 6 million records before I aborted it <sigh />.
> >
> > I'm certain this can be done ... I seem to remember a similar process from
> > the DB2 corporate days ... but I just cannot wrap my head around it.
> > Anybody have any ideas, please?
> >
> > Make a good day ...
> >                                   ... barn

> --
> Stefan Kuhn M. A.
> Cologne University BioInformatics Center (http://www.cubic.uni-koeln.de)
> Tel: +49(0)221-470-7428   Fax: +49 (0) 221-470-7786
> My public PGP key is available at http://pgp.mit.edu

> --
> MySQL General Mailing List
> For list archives: http://lists.mysql.com/mysql
> To unsubscribe:    http://lists.mysql.com/mysql?unsub=1

Thread
Find records not in many-to-many table?barney25 Mar
  • Re: Find records not in many-to-many table?Stefan Kuhn25 Mar
  • Re: Find records not in many-to-many table?sheeri kritzer27 Mar
Re: Find records not in many-to-many table?barney26 Mar
  • Re: Find records not in many-to-many table?Peter Brawley26 Mar
  • Re: Find records not in many-to-many table?Michael Stassen26 Mar
  • Re: Find records not in many-to-many table?Stefan Kuhn26 Mar
Re: Find records not in many-to-many table?barney26 Mar