-- Your SQL goes here
create table kecheng_repeat
(
    id              varchar not null
        primary key
        unique,
    kecheng_root_id varchar not null,
    kecheng_id      varchar not null,
    kecheng_type    varchar,
    start_from      timestamp,
    end_by          timestamp,
    repeat_start    timestamp
);

comment on column kecheng_repeat.kecheng_type is 'STUDENT或者TEACHER';

comment on column kecheng_repeat.start_from is '课程当天开始时间';

comment on column kecheng_repeat.end_by is '课程的当天结束时间';

comment on column kecheng_repeat.repeat_start is '不需要`repeat_end`了，因为同一组`kecheng_root_id`的数据按照`repeat_start`时间排列，后一个就是前一个的end时间。';