Vấn đề khi đếm các giá trị rỗng và sau đó hợp nhất chúng với các hàng hiện có

Loại lộn xộn và rất có thể có thể được cải thiện

;With RawData AS
(
    select * from @t
)
,Ranked1 as
(
    select *, RANK() OVER (PARTITION BY GroupId, RowID ORDER BY ID, GroupId, RowID) R from @t
)
,Ranked2 as
(
    select *, R - RANK() OVER (PARTITION BY GroupId, RowID ORDER BY ID, GroupId, RowID) R2 from Ranked1
    where Data is null
)
,Ranked3 as
(
    select MIN(ID) as MinID, GroupId, RowID, R2, COUNT(*) C2 from Ranked2
    group by GroupId, RowID, R2
)
,Ranked4 as
(
    select RD.ID, RD.GroupId, RD.RowID, ISNULL(Data, C2) as C3 from RawData RD
    left join Ranked3 R3 on RD.ID = R3.MinID and RD.GroupId = R3.GroupId and RD.RowID = R3.RowID
    where ISNULL(Data, C2) is not null
)
,Grouped as
(
    select GroupId, RowID,
        (
            select isnull(C3, '') from Ranked4 as R41
            where R41.GroupId = R42.GroupId and R41.RowID = R42.RowID
            order by GroupId, RowID for xml path('')
        ) as C4
    from Ranked4 as R42
    group by GroupId, RowID
)
    select GroupId,
        stuff((
            select ',' + C4 from Grouped as G1
            where G1.GroupId = G2.GroupId
            order by GroupId for xml path('')
        ), 1, 1, '')
    from Grouped G2
    group by GroupId