ALTER TABLE `#__djc2_producers_extra_fields` 
ADD `filterable` INT NOT NULL DEFAULT '0' AFTER `required`, 
ADD `filter_type` VARCHAR(255) NULL AFTER `filterable`, 
ADD `searchable` INT NOT NULL DEFAULT '0' AFTER `filter_type`, 
ADD `sortable` INT NOT NULL DEFAULT '0' AFTER `searchable`;

ALTER TABLE `#__djc2_producers_extra_fields` ADD INDEX `idx_filterable` (`filterable`);
ALTER TABLE `#__djc2_producers_extra_fields` ADD INDEX `idx_sortable` (`sortable`);
ALTER TABLE `#__djc2_producers_extra_fields` ADD INDEX `idx_searchable` (`searchable`);
