我收到此错误ORA-00907：错过右括号

Question

create table passenger(pnr number(10) primary key,
trainnumber number(5) foreign key references train(trainnumber),
noofseats number(4),
price number(4),
doj varchar2(10))

ORA-00907：缺少右括号

Answer 1

foreign key表达式是多余的（读：错误）。语法只是添加references：

create table passenger(pnr number(10) primary key,
trainnumber number(5) references train(trainnumber), -- here
noofseats number(4),
price number(4),
doj varchar2(10))

Answer 2

将yout CREATE TABLE语句更改为如下所示

create table passenger(pnr number(10) primary key,
trainnumber number(5), 
noofseats number(4),
price number(4),
doj varchar2(10),
foreign key (trainnumber) references train(trainnumber))