Table: golf_tournament_results_5
Columns: date
winning_score
to_par
margin_of_victory
runner_s_up

Question: Which date was the event that Yani won in a playoff over Yueh-Chyn Huang?
SQL: SELECT "date" FROM golf_tournament_results_5 WHERE "margin_of_victory" = 'playoff' AND "runner_s_up" = 'yueh-chyn huang'