CREATE TABLE `knowledge_point_prerequisites` ( `knowledge_point_id` varchar(128) NOT NULL, `prerequisite_kp_id` varchar(128) NOT NULL, `created_at` timestamp NOT NULL DEFAULT (now()), CONSTRAINT `knowledge_point_prerequisites_knowledge_point_id_prerequisite_kp_id_pk` PRIMARY KEY(`knowledge_point_id`,`prerequisite_kp_id`) ); --> statement-breakpoint ALTER TABLE `knowledge_point_prerequisites` ADD CONSTRAINT `kp_prereq_kp_fk` FOREIGN KEY (`knowledge_point_id`) REFERENCES `knowledge_points`(`id`) ON DELETE cascade ON UPDATE no action;--> statement-breakpoint ALTER TABLE `knowledge_point_prerequisites` ADD CONSTRAINT `kp_prereq_prereq_fk` FOREIGN KEY (`prerequisite_kp_id`) REFERENCES `knowledge_points`(`id`) ON DELETE cascade ON UPDATE no action;--> statement-breakpoint CREATE INDEX `kp_prereq_kp_idx` ON `knowledge_point_prerequisites` (`knowledge_point_id`);--> statement-breakpoint CREATE INDEX `kp_prereq_prereq_idx` ON `knowledge_point_prerequisites` (`prerequisite_kp_id`);