user: Question: What's the transfer window that ends in 2012?
Columns: ['Nat.', 'Name', 'Moving from', 'Type', 'Transfer window', 'Ends']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['NED', 'Van der Vaart', 'Hamburger SV', 'Transfer', 'Summer', '2013']
SQL:

assistant: SELECT "Transfer window" FROM "Table" WHERE "Ends" = '2012';