Once again, unusable data.  We need CREATE TABLE and INSERT statement(s), not a picture/"splat" of data on a screen.

So go ahead and do it.  Not sure specifically how a tally table is going to help here.  Besides, a tight loop should likely perform well enough on a string...

I think this code follows all the restrictions for natively compiled procs:

declare @byte tinyint;
declare @bad_chars char(33);
declare @new_string varchar(255);
declare @string varchar(255);
declare @string_len tinyint;
declare @string_replacement_char char(1);

set @bad_chars = '['...

I agree that you should only store attributes as numeric types if you plan on doing math on them, but if you are using only surrogate keys as you...

I agree that the model is not technically valid.  But I take it this is more a class / fictional "design" than a real-world implementation.

For many practical reasons, just use an int like the rest of the world does.  Besides which, the SQL DDL Celko gave above: "allow stuff like "sauerkraut" to be a[n...

I've added comments to your code below.  Some of the code is invalid and/or doesn't make sense.

create procedure AppendAccountCommissionHistory
as
begin
  begin
    insert into...

You could create a combined table.  I assume (perhaps wrongly, if so, correct me) that you will have fewer than 10 professors in the table and therefore you intend that...

SELECT ZipCode, COUNT(DISTINCT DATEADD(MONTH, DATEDIFF(MONTH, 0, UCLogTimeStamp), 0)) AS 'No. months'

FROM #mytable

GROUP BY ZipCode

I'm so sorry guys, wrong CASE

(CASE WHEN CAST(DH.OPENING_HOUR_H AS INT) BETWEEN 10 AND 16 THEN 'Lunch' WHEN CAST(DH.OPENING_HOUR_H AS INT) BETWEEN 16 AND 19 THEN 'Snack' ELSE 'Dinner'...

Sorry, but a picture of data is useless to us.  Please post usable data, that is, a CREATE TABLE and INSERT statement(s).

It should work I think.  But 0x55555 is an odd number of chars, so the value would actually get set to 0x055555.

Try setting it to 0x555555, that should work more...

I just did a few sample rows, I'm not going to type in all that data.

DROP TABLE IF EXISTS #data;
CREATE TABLE #data ( ENTRY_HOUR tinyint NULL, ENTRY_MINUTE...

You cannot update the value of an identity column.  You would to insert a new row and delete the old row.  That will be way too much overhead.

And, as Thom...

...but I don't think I'll ever be converted to leading commas - I think that's at least partly because I'm an English language pedant and believe that a...