Instead of using a CASE expression (as you were trying) - or stacked OR's: WHERE @mDepth > iif(@tDepth = 0, -1, @tDepth)

Consider: @mDepth >= 0 is equivalent to @mDepth...

The values go into the variables at the top.

You'll note that I declared the variables first, then SET them all together.  I personally think it's much more confusing to mix...

Verify that variable @CopyFromUser includes a valid value.

Add a PRINT statement in the script.  Existing code:

...

From dbo.Operator

Where Operator_Ref = @CopyFromUser

SET @rowcount = @@ROWCOUNT

...

so that you can verify how many INSERTs...

CASE is an expression not a statement.  That means that the result of WHEN or THEN must be a single value.  No operators (>,>=, etc.) and no keywords can be...

I executed the script on an instance with 100s of dbs and it worked fine.  Of course I got the "No insertions made..." message since I didn't have dbs named...

I presume you want to know why, when running under the DP300User1 context, the SP works but the query on it's own does not.

When a SP is created by...

DECLARE @CopyUser varchar(30)
DECLARE @Dbnames varchar(8000)
DECLARE @Sql varchar(8000)
DECLARE @UserOp varchar(30)

SET @Dbnames = 'DB1,DB2,DB3' --<<--!!set these values before running!!--<<--
SET @CopyUser = 'User1' --<<--!!set these values before running!!--<<--
SET @UserOp =...

You should never shrink a database, only shrink a file(s).

It seems as if you have one gigantic data file (very bad idea, btw, you should use multiple data files, but...

You must use the max memory setting when you put more than one instance of SQL on a given box, for the reasons others have stated above.

And, for that many...

CONCAT is not a safe way to do this because different values could appear to be the same.

Do all the columns have to match?  Or just some?

For now,...

You shouldn't use 'n/a' as a "value" in place of NULL. Effectively you're corrupting the data. You should just use NULL itself instead.

If all readers of the table...

That is not advisable as this will always start the job, even when it is disabled !

My point is:  When a sysadmin or "sqlagent job manager" disables a job...

I'm almost certain there's a more efficient way to do this, but I can't think of it now.

;WITH cte_valid_first_dose AS (
    SELECT *
 ...

SELECT 
    US.UID, 
    CASE WHEN COUNT(UD.UID) > 0 THEN 'YES' ELSE 'NO' END AS [UID Loaded],
    CASE...

You can start the job easily from the trigger using:

EXEC msdb.dbo.sp_start_job @job_name = '<your_job_name_here>'

That will just start the job and immediately return to the trigger (that is, I'm confirming that...