Table: hoosier_crossroads_conferences
Columns: school
location
mascot
county
2013_2014_size
year_joined
previous_conference

Question: What was the previous conference for the school that joined in 2000 with a millers mascot?
SQL: SELECT "previous_conference" FROM hoosier_crossroads_conferences WHERE "year_joined" = 2000 AND "mascot" = 'millers'