use strict;
use warnings;
use SQL::Builder::Select;

my $select = new SQL::Builder::Select;

$select->column( '*' )
       ->table( 'main' )
       ->where_ne_or( 'col1' )
       ->where_eq_and( 'col1', 'col2' )
       ->where_logic( 'a and o')
       ->order_by( 'col1' )
       ->limit_value( 10 )
       ->limit_offset( 20 )
       ->debug( 1 );

print $select->return();

##</code><code>##

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