Query to delete patients last visit.

I have a table that contains a list of patient id's and visit years .  For example:

PatientID  VisitYear
A1              1
A1              2
A1              2
A1              3
A1              3
A2              1
A2              2
A2              2
A3              1

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I need Query that will delete ALL the entries for the patients last year.  So the above table would look like

PatientID  VisitYear
A1              1
A1              2
A1              2
A2              1

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soozhAsked:
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awking00Connect With a Mentor Commented:
delete from yourtable as a
where exists
(select b.patientid, max(b.visityear)
 from yourtable as b
 group by b.patientid
 having b.patientid = a.patientid
    and max(b.visityear) = a.visityear);
0
 
ThomasianCommented:
DECLARE @t TABLE (PatientID varchar(10), VisitYear int)

INSERT @t
SELECT 'A1', 1
UNION ALL SELECT 'A1', 2
UNION ALL SELECT 'A1', 2
UNION ALL SELECT 'A1', 3
UNION ALL SELECT 'A1', 3
UNION ALL SELECT 'A2', 1
UNION ALL SELECT 'A2', 2
UNION ALL SELECT 'A2', 2
UNION ALL SELECT 'A3', 1

DELETE T
FROM
	(SELECT  rn=RANK() OVER (PARTITION BY PatientID ORDER BY VisitYear DESC)
	 FROM @t
	) T
WHERE rn=1

SELECT * FROM @t

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0
 
SharathConnect With a Mentor Data EngineerCommented:
Another method.
delete t1
  from YourTable t1
  join (select PatientID,max(VisitYear) VisitYear from YourTable group by PatientID) t2
    on t1.PatientID = t1.PatientID and t1.VisitYear = t2.VisitYear

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