SQL - Displaying entries that are the max of a count?

Question

CREATE TABLE doctor( patient CHAR(13), docname CHAR(30) );

Say I had a table like this, then how would I display the names of the doctors that have

Answer 1

Allowing for any feature in any ISO SQL specification since you did not specify a database product or version, and assuming that the table of patients is called "patients" and has a column called "docname", the following might give you what you wanted:

With PatientCounts As
    (
    Select docname
        , Count(*) As PatientCount
    From patient
    Group By docname
    )
    , RankedCounts As
    (
    Select docname, PatientCount
        , Rank() Over( Order By PatientCount ) As PatientCountRank
    From PatientCounts
    )
Select docname, PatientCount, PatientCountRank
From RankedCounts 
Where PatientCountRank = 1