Not sure I really understand your goal here I'm afraid. Sample data (as text) and your expected results will be really helpful here.Could you try to elaborate on your logic...

What do you mean what should you do? If you can't control it there's very little you can do. Have they given a reason for not following good update processes?...

We're missing a piece or 3 of the jigsaw here. Yes, that's the SQL that's raising the error, but that is because that variable does have the value NULL. We...

If my guess is correct, then this is what you are after. You'll need to make use of a Calendar Table, such as the one here.

Your database isn't in compatibility mode 120 or lower is it? (although, you'll...

Have a look at delimitedsplit8k_lead and FOR XML PATH. Have a go, and if you don't succeed post what you tried and what the problem was.

Great example Matt. I think what the OP has experienced here with the attitude from their(?) development team is just further evidence as to why things like injection are still...