ntry' => esc_sql( $parts[0] ),
						'state'   => esc_sql( $parts[1] ),
					);
				}
			} else {
				$countries[] = esc_sql( $location );
			}
		}

		$conditions = array();

		// Build country:state pair conditions.
		if ( ! empty( $country_state_pairs ) ) {
			$pair_conditions = array();
			foreach ( $country_state_pairs as $pair ) {
				if ( $is_include ) {
					$pair_conditions[] = "({$customer_lookup_table}.country = '{$pair['country']}' AND {$customer_lookup_table}.state = '{$pair['state']}')";
				} else {
					$pair_conditions[] = "({$customer_lookup_table}.country != '{$pair['country']}' OR {$customer_lookup_table}.state != '{$pair['state']}')";
				}
			}
			$pair_connector = $is_include ? ' OR ' : ' AND ';
			$conditions[]   = '(' . implode( $pair_connector, $pair_conditions ) . ')';
		}

		// Build country-only conditions.
		if ( ! empty( $countries ) ) {
			$operator     = $is_include ? 'IN' : 'NOT IN';
			$conditions[] = "{$customer_lookup_table}.country {$operator} ('" . implode( "','", $countries ) . "')";
		}

		if ( empty( $conditions ) ) {
			return '';
		}

		// Combine conditions with OR for includes, AND for excludes.
		$connector = $is_include ? ' OR ' : ' AND ';

		return '(' . implode( $connector, $conditions ) . ')';
	}

	/**
	 * Initialize query objects.
	 */
	protected function initialize_queries() {
		$this->clear_all_clauses();
		$table_name     = self::get_db_table_name();
		$this->subquery = new SqlQuery( $this->context . '_subquery' );
		$this->subquery->add_sql_clause( 'from', $table_name );
		$this->subquery->add_sql_clause( 'select', "{$table_name}.customer_id" );
		$this->subquery->add_sql_clause( 'group_by', "{$table_name}.customer_id" );
	}
}