Thread: query help
This seems like such a basic function that I'm sure I am missing something fundamental. I have a table, say xref, whose columns are primary key values for other tables. Some of theses keys may be NULL for a given row in xref. I want to create a query that returns the corresponding entries in the other tables. xref: drug_id | function_id|syst_id |text_id -------------------------------------- d0001 | 2 | 3 | 3423 d0001 | 5 | | 5678 d0056 | 3 | 5 | system_id: syst_id | syst_desc ------------------- 3 | renal 4 | hepatic 5 | respiratory clinical_text: text_id| clinical_text ----------------------------------- 3423 | 'some medical mumbo jumbo' 5678 | 'more of the same' I want the syst_desc and clinical_text (plus other similar data from tables not shown) given a drug_id and function_id. Any help? Thanks a bunch, Jeff Patterson The Melanoma Patients' Information Page http://www.mpip.org -- Jeff Patterson Site Administrator The Melanoma Patients' Information Page http://www.mpip.org/
On Fri, 7 Sep 2001, Jeff Patterson wrote: > This seems like such a basic function that I'm sure I am missing something > fundamental. I have a table, say xref, whose columns are primary key values for > other tables. Some of theses keys may be NULL for a given row in xref. I want > to create a query that returns the corresponding entries in the other tables. > > xref: > drug_id | function_id|syst_id |text_id > -------------------------------------- > d0001 | 2 | 3 | 3423 > d0001 | 5 | | 5678 > d0056 | 3 | 5 | > > system_id: > syst_id | syst_desc > ------------------- > 3 | renal > 4 | hepatic > 5 | respiratory > > clinical_text: > text_id| clinical_text > ----------------------------------- > 3423 | 'some medical mumbo jumbo' > 5678 | 'more of the same' > > I want the syst_desc and clinical_text (plus other similar data from tables not > shown) given a drug_id and function_id. Something like (untested) select drug_id, function_id, syst_desc, clinical_text from (xref left outer join system_id using (syst_id)) left outer join clinical_text using (text_id);
Jeff Patterson wrote:
> This seems like such a basic function that I'm sure I am missing something
> fundamental. I have a table, say xref, whose columns are primary key
> values for other tables. Some of theses keys may be NULL for a given row
> in xref. I want to create a query that returns the corresponding entries
> in the other tables.
>
> xref:
> drug_id | function_id|syst_id |text_id
> --------------------------------------
> d0001 | 2 | 3 | 3423
> d0001 | 5 | | 5678
> d0056 | 3 | 5 |
>
> system_id:
> syst_id | syst_desc
> -------------------
> 3 | renal
> 4 | hepatic
> 5 | respiratory
>
> clinical_text:
> text_id| clinical_text
> -----------------------------------
> 3423 | 'some medical mumbo jumbo'
> 5678 | 'more of the same'
>
> I want the syst_desc and clinical_text (plus other similar data from
> tables not shown) given a drug_id and function_id.
>
> Any help?
If I understand you correctly, you want the query to return the syst_desc
and clinical_text fields where either or both are available? (and not just
where both are available)?
If so a LEFT JOIN may be your best friend. The statement could look like
this:
SELECT system_id.syst_desc,
clinical_text.clinical_text
FROM xref
LEFT JOIN system_id
ON xref.syst_id=system_id.syst_id
LEFT JOIN clinical_text
ON xref.text_id=clinical_text.text_id
WHERE xref.drug_id=? <- insert query value here
AND xref.function_id=? <- and here
(disclaimer: statement untested)
The values not available will be returned as NULL.
> Thanks a bunch,
a bunch of what? ;-)
HTH
Ian Barwick
--
Ian Barwick - Developer
http://www.akademie.de
Remove SUNGLASSES to reply ;-)