I can't see a reason. I assume none of the columns referenced are indeterministic computed or view columns? Any float (imprecise) data? - I'm clutching at straws now...

It's quite a big topic. Here's a basic answer to your question.

You can view query plans in teh graphical viewer in QA, or as text in the results window/profiler/etc.

In the graphical...

Or:

select

t1.vc_col, V.stub

Based on the sample data from one of the above examples, this is a rough-and-ready outline of teh kind of code you could use. Obviously needs tidying up, but you...

Your explanation makes school and site sound like effectively the same thing, but earlier you said they weren't. Post the DDL for your tables.

Don't use a cursor. The tables you mention don't provide enough information to achieve the result you want. Analysis:

calendar:

date,

isweekend,

isholiday

 

semester:

(schoolid?)

start,

end

 

school:

How about putting this code in a trigger or sp to run when the db list is updated:

declare

@sql nvarchar(4000)

Schedule it to run off-peak, if you have a peak. You might want to look at partitioning your table.  How come you are deleting so much data? Are you archiving...

One would need to know how 'site' relates to 'school'. The DDL would help. A hint: you might want to try using a left (outer) join to exclude certain records.

select pt.name

from positions_table pt

where pt.position_name in

 (select distinct ot.position_name

    from old_table ot)

group by  pt.name

having count(distinct pt.id) > 1

You will need to be sure that you can treat position_name in the positions_table as unique.

The least stringent check you can make, in case it's of any use:

select ot.name

from old_table ot

where ot.position_name...

sorry, should be:

 

select

 tab.id

,tab.description

,tab.stuff

,@month M

,case @month

 when 1 then tab.M1

 when 2 then tab.M2

...

 when 12 then tab.M12 M_total

from

whatevertable tab

I half-changed it from...

as a short-term fix (until you implement the above recommendation, perhaps with a table holding yearid, monthid, your float value and a FK back to the original table), you can...

Sorry my mistake. That was a reconstruction of what we think the original code could have looked like?