I have another CASE statement, similar but different, with which I am struggling.

Here's the case statement:

, AcctNum = CASE

When [Obj Acct] = 0 then [Sub]

When [Sub] = 0 then [Obj Acct]

Else [Obj Acct] + '.' + [Sub]

End

FYI

[Obj Acct] is nvarchar

[Sub] is nvarchar

Because now I am referring to column headings, and not values, eg. [Obj Acct] and [Sub], I think I need slightly different syntax, because the column names don't belong within quotes, but I can't get the transform to accept the way I did it (see below, remains red).

([Copy of Obj Acct]=="0")? [Copy of Sub] :(([Copy of Sub]=="0")?[Copy of Obj Acct]: [Copy of Obj Acct]+"."+ [Copy of Sub]))

Can you help me convert this second CASE statement into a Derived Column transform expression? Thx

Thanks.