Query
CREATE TABLE `campaign` (
`id` text PRIMARY KEY,
`channel` text NOT NULL,
`category` text,
`survey_id` text,
`created_at` integer DEFAULT (CURRENT_TIMESTAMP),
`closed_at` integer,
`replaced_by_id` text,
`click` integer DEFAULT 0,
`buy` integer DEFAULT 0,
`comment` text,
CONSTRAINT `fk_campaign_survey_id_survey_id_fk` FOREIGN KEY (`survey_id`) REFERENCES `survey`(`id`),
CONSTRAINT `fk_campaign_replaced_by_id_campaign_id_fk` FOREIGN KEY (`replaced_by_id`) REFERENCES `campaign`(`id`)
)