Trim it within the SELECT statement:

--insert records into $Sheet1 of Template
SET @SqlCmd =    
'INSERT OPENDATASOURCE   
( ''Microsoft.ACE.OLEDB.12.0'',''Data Source=' + @ServerShare + '\' + @ExportFileName...

There should be some way to copy the file even with the "busy" flag on.  Then open the copy, not the original.

That is, the logic becomes:
check for...

For 3 varchar values, it's tricky, and I'd have to do some testing/experimenting first. 

For 3 numeric values, it's easy to list all 3.

For only 2 values of...

It looked you also wanted to list the specific values found.

That's easy for two values, much trickier for 3 (3 numeric values is easy, but not 3 char...

SELECT pid
FROM @table1
GROUP BY pid
HAVING COUNT(DISTINCT gcode) = 3

I don't understand why you don't have p1 and p3 in your result set.

Would have to see the query plan to be sure, but it seems like SQL may be doing an implicit conversion on the date column, which would cause big performance...

It seems like maybe something is blocking the "slow" run, although I'm not sure what it would be.

You don't need to do an explicit transaction.  Once you put the level into effect, it will stay in effect until/unless you explicitly change/override it.

SET TRANSACTION ISOLATION LEVEL...

Divide it by 1000, to add seconds, so it seems based on the value returned:

SELECT DATEADD(SECOND, (1551279347054/1000), '19700101')

If you need to keep the milliseconds, you can...

Did you look at / compare the query plans?

The estimated plan will be the actual plan.  What's missing from the estimated plan is the actual row counts; in an estimated plan, naturally the query didn't actually run, so...

Certain SQL settings being different can cause a separate execution plan to be required.  For example, QUOTED_IDENTIFIER ON vs QUOTED_IDENTIFIER OFF would definitely cause that.  Try explicitly setting all of...

If you want to start over on the design, then start over on the logical design process.  The existing table has no relevance to that process.

Lay out the...