How can I select the entire row when using max - sql

Question

I have a table with the following columns:
SignatureID
PatientID
PatientVisitID
TreatAuthDate
HIPAADate
DrugTestDate
Now I have the following Select statement:
SELECT *
FROM tblSignature
WHERE PatientID = 12345
This select statement returns 8 rows. What I need to accomplish is getting the MAX TreatAuthDate - and with that MAX TreatAuthDate I need the PatientVisitID. Then I need the same type of information for the HipaaDate and DrugTestDate. How can I do this?

Answer 1

SELECT TOP 1 *
FROM tblSignature
WHERE PatientID = 12345
ORDER BY
TreatAuthDate DESC
To get three last results for different definitions of "last", use this:
SELECT *
FROM (
SELECT TOP 1 'LastThreatAuth' AS which, ts.*
FROM tblSignature ts
WHERE PatientID = 12345
ORDER BY
TreatAuthDate DESC
) SrcTreatAuth
UNION ALL
SELECT *
FROM (
SELECT TOP 1 'LastHIPAA' AS which, ts.*
FROM tblSignature ts
WHERE PatientID = 12345
ORDER BY
HIPAADate DESC
) SrcHIPAA
UNION ALL
SELECT *
FROM (
SELECT TOP 1 'LastDrugTest' AS which, ts.*
FROM tblSignature ts
WHERE PatientID = 12345
ORDER BY
DrugTestDate DESC
) SrcDrugTest

Answer 2

SELECT patientid, max(Treatauthdate), max (HippaDAte) , max (DrugTestDate)
FROM tblSignature
WHERE PatientID = 12345
group by patientid
Note you can't ask for signatureid in this case as you would not filter any records out (I'm making the assumption signatureid is your PK). Further to get the max of each date per patient, it is likely they are each on a differnt row of the table so would not have the same signatureid.
To get the visit date for each type might be more difficult as each may be a separate visit.
try something like
select a.patientid, Treatvisitdate, Treatauthdate,Hippavisitdate, HippaDate, DrugTestvisitdate,
DrugTestDate
(SELECT patientid, patientvisitdate as Treatvisitdate, max(Treatauthdate) as Treatauthdate
FROM tblSignature
WHERE PatientID = 12345
group by patientid,patientvisitdate)a
join
(SELECT patientid, patientvisitdate as Hippavisitdate, max(HippaDate) as HippaDate
FROM tblSignature
WHERE PatientID = 12345
group by patientid,patientvisitdate) b on a.patientid = b.patientid
join
(SELECT patientid, patientvisitdate as DrugTestvisitdate, max(DrugTestDate) as DrugTestDate
FROM tblSignature
WHERE PatientID = 12345
group by patientid,patientvisitdate) c on a.patientid = c.patientid
YOu might need left joins if some of the dates might not be in there.