CREATE TABLE table_19846 ("No." FLOAT, "Date" TEXT, "Tournament" TEXT, "Winning score" TEXT, "To par" TEXT, "Margin of victory" TEXT, "Runner-up" TEXT)

The tournament Buick Classic occured on what dates?
SELECT "Date" FROM table_19846 WHERE "Tournament" = 'Buick Classic'
SELECT "Date" FROM "table_19846" WHERE "Tournament" = 'Buick Classic'