Question

I have the following tables:

   TableT1                             TableT2

id           name                 mid  id    visitdate       
4            jack                  1   4     2012/01/22          
5            john                  2   5     2012/01/21            
6            mary                  3   6     Null   
                                           4   5     2012/02/21

I have join this two table.. for each “id” I have to show only one record if he has multiple visit date..

Using below query I m getting record as I want

 select id,name 
 from TableT1 
 left join
 ( 
   SELECT  id,MAX(visitdate) AS visitdate 
   FROM TableT2 
   GROUP BY id
 )as Last_Visit on TableT1.id=Last_Visit.id 
 order by TableT1.name,Last_Visit.visitdate Desc

My problem is to find out rownumber for each id(coloumn) and chk in condition RowNumber >=1 AND RowNumber<=3.

Answer 1

This should give you only the last visitdate per id and only if this id has multiple visits.

WITH cte AS(
    SELECT id
    , visitdate 
    , ROW_NUMBER()OVER(Partition By id Order By visitdate DESC)As VisitNum
   FROM TableT2 
)
select  TableT1.id, TableT1.name
       ,cte.visitdate , cte.VisitNum
 from TableT1 INNER JOIN cte 
    ON TableT1.id=cte.id  AND cte.VisitNum=1 
        AND EXISTS(SELECT NULL FROM cte c2 WHERE c2.id=cte.id AND c2.VisitNum>1)