user: Question: Who was Constructor for rider Marco Melandri?
Columns: ['Team', 'Constructor', 'Motorcycle', 'Tyre', 'Rider', 'Rounds']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Ducati Marlboro Team', 'Ducati', 'Ducati Desmosedici GP8', 'B', 'Casey Stoner', 'All']
SQL:

assistant: SELECT "Constructor" FROM "Table" WHERE "Rider" = 'Marco Melandri';