my $preql = <<'PREQL'
 *      SELECT
 *          Name
 *      FROM
 CUST       Customer
 SALE       Sales
 *      WHERE
 CUST      CustID = ?customer_id?
 SALES     SalesID = ?sales_id?     
PREQL

my ($query, @params) = DBIx::PreQL->build_query(
     query => $preql,
     data => {
        sales_id => $salesid,
        customer_id => $custid,
     },
    wanted => $x > 10 ? 'CUST' : 'SALES'
 );

my $got = $db->selectall_hashref( $query, @params );