BP_XProfile_Field::update_position( int $field_id, int|null $position = null, int|null $field_group_id = null )

	public static function update_position( $field_id, $position = null, $field_group_id = null ) {
		global $wpdb;

		// Bail if invalid position or field group.
		if ( ! is_numeric( $position ) || ! is_numeric( $field_group_id ) ) {
			return false;
		}

		// Get table name and field parent.
		$table_name = buddypress()->profile->table_name_fields;
		$sql        = $wpdb->prepare( "UPDATE {$table_name} SET field_order = %d, group_id = %d WHERE id = %d", $position, $field_group_id, $field_id );
		$parent     = $wpdb->query( $sql );

		// Update $field_id with new $position and $field_group_id.
		if ( ! empty( $parent ) && ! is_wp_error( $parent ) ) {

			// Update any children of this $field_id.
			$sql = $wpdb->prepare( "UPDATE {$table_name} SET group_id = %d WHERE parent_id = %d", $field_group_id, $field_id );
			$wpdb->query( $sql );

			// Invalidate profile field cache.
			wp_cache_delete( $field_id, 'bp_xprofile_fields' );

			do_action( 'xprofile_updated_field_position', $field_id, $position, $field_group_id );

			return $parent;
		}

		return false;
	}