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hi ken,

you shoudl be able to do this subquery:

select id from books where id not in (select subj_code from subjects);

to get all the books that dont' have subject codes

that is, if subj_code and book_id are linked...

hth

--
Susan Teague Rector
Web Applications Manager
VCU Libraries: Library Information Systems
804.827.3554 | [log in to unmask]


Ken Irwin wrote:
> Hi folks,
>
> I'm trying to put together a MySQL query to do something I don't know
> how to do: get a list of materials that DON'T show up in a relational
> table.
>
> For example, 3 tables:
>
> 1) lib.books : lots of bib data including book_id
> 2) lib.subjects: subj_code, selector, subject_name
> 3) relational: lists book_id & subj_code
>
> I want to generate a list of books that are in lib.books that doesn't
> have any subjects assigned to it.
>
> I could do this with 2 queries, but it gets unwieldy: get a list of
> distinct book_ids and AND/NOT them all together like:
> SELECT * FROM books WHERE book_id != '4' and book_id != '7'...
> That works on really small sets, but I don't want to go that route.
>
> Is there a savvy way to structure this MySQL query. I don't even know
> the language to use to look for this information.
>
> Thanks for any help you can provide!
> Ken
>
> --
> Ken Irwin
> Reference Librarian
> Thomas Library, Wittenberg University