oracle - I want to have only 3 columns (departure_City_Id, arrival_City_Id, Emp_number). However, when I come to insert value , it says that I have 4 columns -

for epms table, want have 3 columns (departure_city_id, arrival_city_id, emp_number). however, when come insert value, says have 4 columns. 1 city_id. want avoid having city_id column in table. declare because need fk.

create table city ( city_id char(3), state varchar(30), primary key (city_id) );   create table emps (  emp_number varchar(30) primary key,  city_id char(3),  departure_city_id char(3), arrival_city_id char(3),   foreign key (city_id)     references city(city_id),   foreign key (city_id)     references city(city_id) ); 

this pretty straightforward, specify e.g. , foreign key (arrival_city_id) references city(city_id) , you'll index.

create table emps (   emp_number          varchar(30)  not null,   city_id             char(3)      not null,   departure_city_id   char(3)      not null,   arrival_city_id     char(3)      not null,   primary key (emp_number),   key city_id (city_id),   key departure_city_id (departure_city_id),   key arrival_city_id (arrival_city_id),   constraint emps_ibfk_1 foreign key (city_id) references city (city_id),   constraint emps_ibfk_2 foreign key (departure_city_id) references city (city_id),   constraint emps_ibfk_3 foreign key (arrival_city_id) references city (city_id) ) engine=innodb default charset=utf8mb4;