user: Question: When Hale Irwin is the winner what is the margin of victory?
Columns: ['Year', 'Tournament', 'Winner', 'Margin of victory', 'Winners share ( $ )', 'Par', 'Course length']
Types: ['real', 'text', 'text', 'text', 'real', 'real', 'text']
Sample row: [1949.0, 'U.S. Open', 'Cary Middlecoff', '1 stroke', 2000.0, 71.0, 'yd (m)']
SQL:

assistant: SELECT "Margin of victory" FROM "Table" WHERE "Winner" = 'Hale Irwin';