user: Question: Which of the Private colleges is the oldest, and whose nickname is the Mountaineers?
Columns: ['Institution', 'Nickname', 'Location', 'Founded', 'Type', 'Enrollment']
Types: ['text', 'text', 'text', 'real', 'text', 'real']
Sample row: ['Alice Lloyd College', 'Eagles', 'Pippa Passes, Kentucky', 1923.0, 'Private', 600.0]
SQL:

assistant: SELECT "Founded" FROM "Table" WHERE "Type" = 'Private' AND "Nickname" = 'Mountaineers';