formulas skipping empty cells

I 'm using a formula to join to cells "A" and "B" (text) and I"m using the following formula =A&,","&B (which i'm using to join first name and last name). I have about 3000 records that I need to run this formula but I want to have a macro or code that will apply that formula only on those rows that have data. Otherwise if empty then skipp the row.

you have are a great help and I hope you guys can help me with one. thanks a bunch in advace.