title: Error during compilation is department_id invalid identifier
body: <pre><code>create table student 
  (
      Student_id number(30), 
      student_name varchar(30), 
      city varchar(30), 
  
      constraint pk primary key(student_id), 
      constraint department_id 
          foreign key(department_id) references department(department_id) 
  );
  </code></pre>