Well, it looks like the sodium ions and chloride ions are just hanging out together on both sides of the equation, so they're not really doing anything exciting. The real star of the show here is the zinc cation and the oxalate anion. They come together to form solid zinc oxalate. So, we can simplify the equation to:
Zn2+(aq) + C2O42-(aq) → ZnC2O4(s)
That's the net ionic equation. The sodium and chloride ions are just the "extras" in this reaction. They're like the background dancers who don't really contribute much to the main act.