create table tv_channels 
(
   id                 INTEGER              not null,
   name               VARCHAR2(100)        not null,
   desc               VARCHAR2(1000),
   constraint PK_TV_CHANNELS primary key (id),
   constraint AK_KEY_2_TV_CHANN unique (name)
);


create table tv_shows 
(
   id                 INTEGER              not null,
   name               VARCHAR2(100)        not null,
   desc               VARCHAR2(1000),
   constraint PK_TV_SHOWS primary key (id)
);

create table program_guide 
(
   tv_channel_id      INTEGER              not null,
   tv_show_id         INTEGER              not null,
   start_time         DATE                 not null,
   end_time           DATE                 not null,
   constraint CKT_PROGRAM_GUIDE check (start_time<stop_time)
);


create index Index_1 on program_guide (
   tv_channel_id ASC,
   tv_show_id ASC
);

alter table program_guide
   add constraint FK_PROGRAM__REFERENCE_TV_CHANN foreign key (tv_channel_id)
      references tv_channels (id);

alter table program_guide
   add constraint FK_PROGRAM__REFERENCE_TV_SHOWS foreign key (tv_show_id)
      references tv_shows (id);

constraint AK_KEY_1_SUPERVIS unique (department_id, proff_id, group_id, student_id)