Question

I have some record as under for tblFiltered

ID  RowID   Position    Data
1   1        a1          R
1   1        b1          N
1   1        e1          K
1   1        g1          N
1   1        h1          R
1   2        b2          T
1   2        c2          B
1   2        d2          Y
1   2        f2          F

And the table tblComplete has the below data

RowID   Position    Data
1         a1        NULL
1         b1        NULL
1         c1        NULL
1         d1        NULL
1         e1        NULL
1         f1        NULL
1         g1        NULL
1         h1        NULL
2         a2        NULL
2         b2        NULL
2         c2        NULL
2         d2        NULL
2         e2        NULL
2         f2        NULL
2         g2        NULL
2         h2        NULL

The desired output is

ID  RowID   Position  CompleteData
1   1         a1           R
1   1         b1           N
1   1         c1           NULL
1   1         d1           NULL
1   1         e1           K
1   1         f1           NULL
1   1         g1           N
1   1         h1           R
1   2         a2           NULL
1   2         b2           T
1   2         c2           B
1   2         d2           Y
1   2         e2           NULL
1   2         f2           F
1   2         g2           NULL
1   2         h2           NULL

That means the records that are not in tblFiltered will be taken from tblCompelete and it will be filled.
e.g. c1, d1 and f1 are not in tblFiltered and henceforth are taken from tblCompelte and being added to the resultant output.

I have written the query

select t.ID,c.RowID,c.Position,
 CompleteData = case when t.Data IS null then null else t.data end
from @CompleteData c
left join @tblFiltered t 
on c.Position = t.Position

whose output is

ID    RowID Position    CompleteData
1       1       a1               R
1       1       b1               N
NULL    1       c1               NULL
NULL    1       d1               NULL
1       1       e1               K
NULL    1       f1               NULL
1       1       g1               N
1       1       h1               R
NULL    2       a2               NULL
1       2       b2               T
1       2       c2               B
1       2       d2               Y
NULL    2       e2               NULL
1       2       f2               F
NULL    2       g2               NULL
NULL    2       h2               NULL

As can be seen, I am unable to set the ID. Also, if the ID’s become > 1 in tblFiltered, then how will I keep track of that?

DDL are

Declare @tblFiltered table(ID int,RowID int,Position varchar(10),Data varchar(10))     
Insert into @tblFiltered     
Select 1,1,'a1','R' union all     
Select 1,1,'b1','N' union all     
Select 1,1,'e1','K' union all     
Select 1,1,'g1','N' union all     
Select 1,1,'h1','R' union all     
Select 1,2,'b2','T' union all     
Select 1,2,'c2','B' union all     
Select 1,2,'d2','Y'  union all   
Select 1,2,'f2','F'

Declare @CompleteData table (RowID int,Position varchar(10),Data varchar(10))
Insert into @CompleteData
select  1, 'a1', Null Union All
select  1, 'b1', Null Union All
select  1, 'c1', Null Union All
select  1, 'd1', Null Union All
select  1, 'e1', Null Union All
select  1, 'f1', Null Union All
select  1, 'g1', Null Union All
select  1, 'h1', Null Union All
select  2, 'a2', Null Union All
select  2, 'b2', Null Union All
select  2, 'c2', Null Union All
select  2, 'd2', Null Union All
select  2, 'e2', Null Union All
select  2, 'f2', Null Union All
select  2, 'g2', Null Union All
select  2, 'h2', Null 
--Select * from @tblFiltered
--Select * from @CompleteData 

Thanks in advance

Answer 1

select 1 as ID,
       C.RowID,
       C.Position,
       F.Data
from tblComplete as C
  left outer join tblFiltered as F
    on C.Position = F.Position
order by C.RowID, C.Position