Question

This is linked to my previous Qn

Table A: 
ID  Rank Name 
1   100  Name1 
1    45  Name2 
2    60  Name3 
2    42  Name4 
2    88 Name5 
3    50 name6
3    50 name7

Table B: 
ID FileName 
1  fn1 
2  fn2 
3  fn3

What I want is

1 fn1 name1 
2 fn2 name5 
3 fn3  name6,name7

Here is my code that doesnt deal with the duplciate ranks above, so I get two rows for value 3.

select B.*,A.Name
LEFT JOIN ( SELECT A.Id, MAX(A.Rank)as Rank 
    FROM A 
    GROUP BY A.Id
    ) AS NewA 
            JOIN A 
                on A.Rank = NewA.Rank
                    AND A.ID = NewA.Id
    on NewA.ID = B.ID 

How do I modify this to give me A.name seperated by comma when the ranks are same for a Id?

Thanks

Answer 1

You will need to use a CTE to flatten this out.

This should plug directly into SQL and work with the data given as an example. Obviously, you will need to update the queries for your real data since this is probably not your real schema

create table #tableA (ID int, [rank] int, name varchar(max))
insert into #tableA values(1,100,'Name1')
insert into #tableA values(1,45,'Name2')
insert into #tableA values(2,60,'Name3')
insert into #tableA values(2,42,'Name4')
insert into #tableA values(2,88,'Name5')
insert into #tableA values(3,50,'Name6')
insert into #tableA values(3,50,'Name7')

create table #tableB (ID int, [FileName] varchar(max))
insert into #tableB values(1,'fn1')
insert into #tableB values(2,'fn2')
insert into #tableB values(3,'fn3')

SELECT B.*,A.Name, ROW_NUMBER() OVER (PARTITION BY A.ID ORDER BY A.[rank]) AS RowNum
INTO #RankedTable
FROM #tableB as B
    LEFT JOIN ( 
        SELECT A.Id, MAX(A.Rank)as Rank 
        FROM #tableA AS A 
        GROUP BY A.Id
        ) AS NewA 
    JOIN #tableA AS A
        on A.Rank = NewA.Rank
            AND A.ID = NewA.Id
    on NewA.ID = B.ID 

;WITH ConcatenationCTE (ID, [FileName], Name, RowNum)
AS
(
  SELECT ID, [FileName], Name, RowNum 
  FROM #RankedTable
  WHERE RowNum = 1
  UNION ALL
  SELECT #RankedTable.ID, #RankedTable.[FileName],
          ConcatenationCTE.Name + ',' + #RankedTable.Name AS Name, 
          #RankedTable.RowNum 
  FROM #RankedTable
      JOIN ConcatenationCTE 
          ON ConcatenationCTE.ID = #RankedTable.ID 
              AND ConcatenationCTE.RowNum +1 = #RankedTable.RowNum
)
SELECT ConcatenationCTE.ID, [FileName], Name 
FROM ConcatenationCTE 
        JOIN 
     (SELECT ID, MAX(RowNum) AS RowNum 
      FROM ConcatenationCTE GROUP BY ID) AS FinalValues 
        ON FinalValues.ID = ConcatenationCTE.ID 
            AND FinalValues.RowNum = ConcatenationCTE.RowNum