Trimming Commas

I'm dynamically building an SQL string to do an execute, and keep ending up with a leftover comma, so the string looks like this.

INSERT INTO Software ( Title, Version, Licensing, Total_Licenses, support_phone, support_email, Campuses_Licensed, Comments, support_web, FundingSource, Course_title, Subject, Grade_level, LocalExpert, ACTIVE, CATE, EntryDate,) VALUES ( 'Bob's Super Crappy Software', '4.3', 'labpack', '36', '555', '555', 'Alexander, Bilhartz, Central, Fairmeadows, Hyman, Daniel', 'James is testing this', 'www.bob.com', 'Campus PO', 'Math', 'Math', '4, 5, 6', 'Patrick Williams', '1', '0',)

Both commas are added dynamically and can be trimmed on the fly. I tried using RTRIM(strSQL, ",") but this didn't work.I put the fields into an array and tried to add only commas to all but the last entry, but that also didn't work.