Question

I have migrated an Access DB to MSSql server 2008 and found some anomalies from the old database. On both DBs IDs are auto incremental and should be in line with Date. But as shown below, some have been saved in the wrong chronological order.

**Access:**
ID  FileID  DateOfTransaction SectionID
64490   95900   02/12/1997  100
64491   95900   04/04/1996  80
64492   95900   25/03/1996  90

**Desired Correct Format:**
ID  FileID  DateOfTransaction SectionID
64492   95900   02/12/1997  100
64491   95900   04/04/1996  80
64490   95900   25/03/1996  90

The PK (ID) table is linked to several other tables with update Cascade set.
I need to group by FileID and sort by DateOfTransaction and update IDs accordingly.

I need some suggestions on how best to tackle this as data is quite sensitive. I have about 50K records to update.

Thanks for reading!

Answer 1

try this query

with cte as
(select * from  (
    select *,ROW_NUMBER() over (partition by FileID 
    order by DateOfTransaction) as row_num
    from t_Transactions) A
join 
    (select ID B_ID, FileID B_FileID,ROW_NUMBER() 
    over (partition by FileID order by ID) as B_row_num
    from t_Transactions) B
on A.row_num=B.B_row_num)

select T.ID [Old_ID], CTE.B_ID [New_ID],
   T.FileID,T.DateOfTransaction,T.SectionID
--update T set T.ID=CTE.B_ID  
from t_Transactions T join cte
on T.ID=CTE.ID
and CTE.B_FileID=T.FileID 

Before updating , you can select and conform the result

This query updates the table as per your requirement. You have mentioned that ID column is linked to several other tables. Please be very careful about this and make sure that updating ID column doesn’t break anything else

SQL Fiddle Demo