文章、课程标签的默认封面

schoolNewsServ/.bin/mysql/sql/createTableLearning.sql

@@ -31,9 +31,7 @@ CREATE TABLE `tb_learning_task_tag` (
   PRIMARY KEY (`id`),
   UNIQUE KEY `uk_task_tag` (`task_id`, `tag_id`),
   KEY `idx_task_id` (`task_id`),
-  KEY `idx_tag_id` (`tag_id`),
-  CONSTRAINT `fk_task_tag_task` FOREIGN KEY (`task_id`) REFERENCES `tb_learning_task` (`task_id`) ON DELETE CASCADE,
-  CONSTRAINT `fk_task_tag_tag` FOREIGN KEY (`tag_id`) REFERENCES `tb_tag` (`tag_id`) ON DELETE CASCADE
+  KEY `idx_tag_id` (`tag_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci COMMENT='学习任务标签关联表';