DEBUG: logic broken up
	'a ', 'AND', ' o'
DEBUG: joining
	AND - 'col1 = ?', 'col2 = ?'
DEBUG: no need to join
	'col1 != ?'
DEBUG: joining
	AND - '(col1 = ?) AND (col2 = ?)', 'col1 != ?'

DEBUG: sql
	SELECT * FROM main WHERE ((col1 = ?) AND (col2 = ?)) AND (col1 != ?) ORDER BY col1 LIMIT 20, 10