3.3.0 add mark_student index

distributed-print/install/mysql/init/teachcloud_db.sql

@@ -1531,6 +1531,7 @@ CREATE TABLE IF NOT EXISTS `mark_student` (
         `exam_end_time` BIGINT(20) NULL COMMENT '考试结束时间',
         `create_id` BIGINT(20) NULL COMMENT '创建人ID',
         PRIMARY KEY (`id`) USING BTREE,
+        UNIQUE KEY `index1` (`exam_id`,`student_code`,`course_paper_id`) USING BTREE,
         UNIQUE KEY `index2` (`exam_id`,`secret_number`) USING BTREE,
         KEY `index3` (`exam_id`,`course_code`,`upload_time`) USING BTREE
         ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='考试考生库';