I have used th case statement to do reverse the values present in the Table

select

case

when MyCol>0 then 0-MyCol

else

abs(MyCol)

end

from dbo.MyTable

The logic here is pretty simple.

I have used a while loop to get the difference between the Min and Max date and then insert the missing records into the table...

I guess the below query will be useful for your problem

select contactdesc,

case

when (donedate is null and getdate()>=duedate) then 1

when donedate is not null then 5

when (donedate is null and...

I believe after deleting the rows You should execute DBCC Reindex and then use dbcc updateusage

Recommend you to do DBCC UPDATEUSAGE on the indexes of the Table .This will ensure that all corrupt/discrepant indexes are fixed.

Hope this will resolve your problem