How to improve this query?

Aliquot table contains columns PatientID, AliquotTypeID, LocationCode,
AliquotNumber. The query is to get the locationCode with minimum
AliquotNumber in a (PatientID and AliquotTypeID) Group.
select locationCode from aliquot a
where a.patientID = 1 and aliquotTypeID = 1 and
a.aliquotNumber = (Select min(aliquotNumber) from aliquot where patientID =
1 and aliquotTypeID= 1 and locationCode is not null)
thanks,Try:
SELECT LOCATIONCODE, MIN(ALIQUOTNUMBER)
FROM ALIQUOT
WHERE PATIENTID = 1 AND ALIQUOTTYPEID = 1 AND LOCATIONCODE IS NOT NULL
GROUP BY LOCATIONCODE
HTH
Jerry
"Caspy" <caspases@.yahoo.com> wrote in message
news:O2fa1rQyFHA.700@.TK2MSFTNGP11.phx.gbl...
> Aliquot table contains columns PatientID, AliquotTypeID, LocationCode,
> AliquotNumber. The query is to get the locationCode with minimum
> AliquotNumber in a (PatientID and AliquotTypeID) Group.
> select locationCode from aliquot a
> where a.patientID = 1 and aliquotTypeID = 1 and
> a.aliquotNumber = (Select min(aliquotNumber) from aliquot where patientID
> = 1 and aliquotTypeID= 1 and locationCode is not null)
> thanks,
>
>|||Thanks for your reply. Because the locationCode is unique for each
AliquotNumber, your query returns multiple rows.
Since the Aliquot table has half million tupples, I just want to limit to 1
visit to this big table when try to retrieve the locationCode with minimum
aliquotNumber in a (patientID and AliquotTypeID) group.
"Jerry Spivey" <jspivey@.vestas-awt.com> wrote in message
news:%23lXiB3QyFHA.1256@.TK2MSFTNGP09.phx.gbl...
> Try:
> SELECT LOCATIONCODE, MIN(ALIQUOTNUMBER)
> FROM ALIQUOT
> WHERE PATIENTID = 1 AND ALIQUOTTYPEID = 1 AND LOCATIONCODE IS NOT NULL
> GROUP BY LOCATIONCODE
> HTH
> Jerry
> "Caspy" <caspases@.yahoo.com> wrote in message
> news:O2fa1rQyFHA.700@.TK2MSFTNGP11.phx.gbl...
>