Rather than a CASE, use the built-in REPLICATE function:

DECLARE @MAX_naam AS varchar(MAX) 
SET @MAX_naam = 22 --(SELECT SUBSTRING(MAX(naam),LEN(MAX(naam))-1,LEN(MAX(naam))) FROM incident); -- = 22
DECLARE @maxnaam_length AS int =...

Ah, but this is a SQL Server forum.  Your q is somewhat off-topic here.  You might want to...

Right, because reorganize only ever needs 1 extra work page, the in_tempdb option is really meaningless for reorg.

SELECT SubmissionGuid
FROM #Subs
GROUP BY SubmissionGuid
HAVING MAX(CASE WHEN QuoteStatus = 1 THEN 1 ELSE 0 END) = 0

To avoid using the user db for index rebuild work space, look into specifying SORT_IN_TEMPDB = ON as part of the index REBUILD.  This is especially true if you have...

I'll assume you have an existing clustered index on the table.  If you do, most likely you'll want to use a clustered columnstore index instead.  To do that, follow these...

For best performance, make sure you have the log table properly clustered.  Specifically, if you intend to delete by log time, as is quite typical, then cluster the table that...

Rather than adding a month and taking away a day to  get the end of month (which is how I have always done it) there is a function called...

I suspect there's some way to do this without recursion, but for now, here's a method using recursion.

DECLARE @amount_to_spend decimal(9, 2)
SET @amount_to_spend = 50.00

;WITH cte_products_by_price AS (
...

;WITH
cte_tally10 AS (
    SELECT * FROM (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) AS numbers(number)
),
cte_tally100 AS (
    SELECT 0 AS number UNION ALL
    SELECT...

I don't think you don't need an explicit COMMIT and ROLLBACK.  In SQL Server, by default each SQL statement that modifies data will be in its own transaction.

Specify "SET XACT_ABORT...

To the first point, there's...

One place to start is reviewing the "Top 10 Avg I/O Queries".  See if anything stands out there.

Next I'd review the index stats.  Looking particularly at missing indexes and the...

OK.  Sorry, my bad, it...

Didn't you already ask this q?!