user: Question: A player was moved to Celtic had an end of what date?
Columns: ['Start date', 'End date', 'Pos.', 'Player', 'To club']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['15 Aug. 07', '31 May 08', 'MF', 'Ishmael Miller', 'West Brom']
SQL:

assistant: SELECT "End date" FROM "Table" WHERE "To club" = 'Celtic';