user: Question: Name the total number of overall for defensive tackle
Columns: ['Round', 'Pick #', 'Overall', 'Name', 'Position', 'College']
Types: ['real', 'real', 'real', 'text', 'text', 'text']
Sample row: [1.0, 22.0, 22.0, 'Don McCauley', 'Running Back', 'North Carolina']
SQL:

assistant: SELECT SUM("Overall") FROM "Table" WHERE "Position" = 'defensive tackle';