user: Question: How many times was Pernell Whitaker an opponent?
Columns: ['Number', 'Name', 'Titles', 'Date', 'Opponent', 'Result', 'Defenses']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'Thomas Hearns', 'WBA Welterweight (147)', '1980-08-02', 'Pipino Cuevas', 'TKO 2/15', 3.0]
SQL:

assistant: SELECT COUNT("Date") FROM "Table" WHERE "Opponent" = 'Pernell Whitaker';