barney
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).
If the join columns have different names, simply change the join to
select FileKey
from dl_files f
left join dl_merges m on f.fileId = m.<whatevercolumnname>
where m.<whatevercolumnname> is null
PB
-----
barney wrote:
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)
Zülpicher Str. 47, 50674 Cologne
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/[EMAIL PROTECTED]
