user: Question: Name the Round which has a Position of Defensive Back and Corey Chavous?
Columns: ['Round', 'Pick', 'Player', 'Position', 'School/Club Team']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [1.0, 3.0, 'Andre Wadsworth', 'Defensive End', 'Florida State']
SQL:

assistant: SELECT "Round" FROM "Table" WHERE "Position" = 'Defensive Back' AND "Player" = 'Corey Chavous';