Google Sheets, question about combining data across columns

I have a Google spreadsheet set up for work with a long list of names, phone numbers, and other data, with each data item in its own column. When I received the original sheet, Last Name was in column B, first name was in C, and middle name is in D. I then combined them into one column (E) using this formula:
=B2 & " " & C2 & " " & D2

I’m trying to figure out how I can add a comma after the last name. I tried a few things, like inserting a comma into the formula, but it didn’t work.

Anyone have any ideas?

Wouldn’t this work?
=B2 & ", " & C2 & " " & D2

That should certainly work – I’ve done it countless times.

There is also another error in the formula, in that if the person has no middle name (a fairly common thing), then the result is an unneeded trailing space. If this matters, you need to modify the formula to handle this.

There are also people that have only a singular name. This may be treated as only a first name or a last name but, whichever the case, you’ll have either a leading comma or trailing comma just dangling there.

Yes, it did work. I was trying to add the comma in the wrong space.

As far as middle names, anyone on the list without a middle name (or initial) has NMN entered.

Thanks, y’all.

Taking this sort of thing a bit further, you get: