user: Question: What was the previous conference for the school that joined in 2000 with a Millers mascot?
Columns: ['School', 'Location', 'Mascot', 'County', '2013-2014 Size', 'Year Joined', 'Previous Conference']
Types: ['text', 'text', 'text', 'text', 'real', 'real', 'text']
Sample row: ['Avon', 'Avon', 'Orioles', '32 Hendricks', 2608.0, 2000.0, 'Mid-State']
SQL:

assistant: SELECT "Previous Conference" FROM "Table" WHERE "Year Joined" = 2000.0 AND "Mascot" = 'Millers';