user: Question: What was the overall draft pick of the player who was a DB and attended college in Iowa?
Columns: ['Round', 'Pick', 'Overall', 'Name', 'Position', 'College']
Types: ['real', 'real', 'real', 'text', 'text', 'text']
Sample row: [1.0, 4.0, 4.0, 'Cal Rossi [a ]', 'RB', 'UCLA']
SQL:

assistant: SELECT "Overall" FROM "Table" WHERE "College" = 'Iowa' AND "Position" = 'DB';