=back
+=head1 CLASS METHODS
+
+=item location_sql KEY => VALUE, ...
+
+Returns an SQL fragment identifying matching tax_rate_location /
+cust_bill_pkg_tax_rate_location records.
+
+Parameters are county, state, city and locationtaxid
+
+=cut
+
+sub location_sql {
+ my($class, %param) = @_;
+
+ my %pn = (
+ 'city' => 'tax_rate_location.city',
+ 'county' => 'tax_rate_location.county',
+ 'state' => 'tax_rate_location.state',
+ 'locationtaxid' => 'cust_bill_pkg_tax_rate_location.locationtaxid',
+ );
+
+ my %ph = map { $pn{$_} => dbh->quote($param{$_}) } keys %pn;
+
+ join( ' AND ',
+ map { "( $_ = $ph{$_} OR $ph{$_} = '' AND $_ IS NULL)" } keys %ph
+ );
+
+}
+
+=back
+
=head1 SUBROUTINES
=over 4