Actually, the development team should have nothing to do with how the data in the db is physically stored.  That's the DBA's job.  (Sorry, just had to say that first.)

I'll...

If you don't need to worry about possible blank chars in the data, you can remove the trimming.  I did it just as a safeguard.

;WITH test_data AS...

SELECT ca.*
FROM dbo.your_table_name
CROSS APPLY (
    SELECT Sector, 2023 AS Period, [2023] AS Value
    UNION ALL
    SELECT Sector, 2024,...

Check to see if the tool has some type of api or other interface that will let you get the SQL from the tool itself.

SELECT *,
    SUM(tran_in - tran_out) OVER(PARTITION BY account_id ORDER BY Year_cal, Month_Cal 
        ROWS BETWEEN UNBOUNDED PRECEDING...

I believe you want decimal(4, 1) rather than (3, 1) (at least I can't see any reason why 100% of one group might...

There is no such thing of any kind built into SQL Server.

If you just want to get rid of all digits in the email address, then:

REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(email_id, '0', ''), '1', ''), '2', ''), '3', ''), ...

Most likely, SQL detected that fewer rows would be returned and therefore changed how it would access those tables based on row estimates.  If the row estimates are off, SQL...

You need to look at your stand-alone (non-proc) query again.  It seems to have an INNER JOIN rather than a LEFT JOIN, at least according to the query plan.

Maybe it will.  SQL can pre-fetch data.  It depends on the specifics of the situation, including your edition of SQL Server.

Since TRUNCATE is more efficient, try it first.

If it doesn't work, then use DELETE.

STRING_AGG isn't available before SQL 2016, right?

Select T1.Itemcode,T1.name ,
    stuff((select ', ' + docno 
        from [order]...

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...