user: Question: Where does the Defensive Back position appear first?
Columns: ['Round', 'Choice', 'Overall', 'Player name', 'Position', 'College']
Types: ['real', 'real', 'real', 'text', 'text', 'text']
Sample row: [1.0, 25.0, 25.0, 'John Ward', 'Offensive Tackle', 'Oklahoma State']
SQL:

assistant: SELECT MIN("Round") FROM "Table" WHERE "Position" = 'Defensive Back';