user: Question: Who was the regular season winner of the 1999 Big Sky Men's Basketball Tournament was the conference tournament?
Columns: ['Conference', 'Regular Season Winner', 'Conference Player of the Year', 'Conference Tournament', 'Tournament Venue (City)', 'Tournament Winner']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Atlantic 10 Conference', 'Temple (East) George Washington (West)', 'Shawnta Rogers , George Washington', "1999 Atlantic 10 Men's Basketball Tournament", 'The Spectrum ( Philadelphia, Pennsylvania )', 'Rhode Island']
SQL:

assistant: SELECT "Regular Season Winner" FROM "Table" WHERE "Conference Tournament" = '1999 Big Sky Men''s Basketball Tournament';