Hi,
As PHV has it, but with additional link between dates to keep the ranking contained to a particular date:
SELECT tblHbInput.Pat_Number, tblHbInput.Code, tblHbInput.Spec_Date, tblHbInput.CRN, tblHbInput.Result, Count(tblHbInput.Pat_Number) AS Rank
FROM tblHbInput INNER JOIN tblHbInput AS...