title: error ORA-02270: no matching unique or primary key for this column-list
body: <p>I'm practicing a lab manual excercise in which I have to create 6 tables. Creation of 5 is
  successful.</p>
  
  <p>But one line is giving error</p>
  
  <pre><code>constraint GRADE_Designation_FK 
     FOREIGN KEY(Designation) References EMPLOYEE(Designation),
  </code></pre>
  
  <p>ERROR at line 7:      </p>
  
  <blockquote>
    <p>ORA-02270: no matching unique or primary key for this column-list</p>
  </blockquote>
  
  <p>Queries of 2 linked tables are</p>
  
  <pre><code>create table EMPLOYEE
  (
      Empno number(4) constraint EMPLOYEE_Empno_PK PRIMARY KEY,
      Name varchar2(10) not null,
      Designation varchar2(50),
      Qualification varchar2(10),
      Joindate date
  );
  
  create table GRADE
  (
      Designation varchar2(50) constraint GRADE_Designation_PK PRIMARY KEY,
      Grade number(2),
      TotalPosts number(4),
      PostsAvailable number(4),
  
      constraint GRADE_Grade_CK  check(Grade between 1 and 20),
      constraint GRADE_PostsAvailable_CK check(PostsAvailable &lt;= TotalPosts),
      constraint GRADE_Designation_FK FOREIGN KEY(Designation) References EMPLOYEE(Designation)
  );
  </code></pre>
  
  <p>Tried</p>
  
  <pre><code>create table GRADE
  (
      Designation varchar2(50) constraint GRADE_Designation_PK PRIMARY KEY,
      Grade number(2),
      TotalPosts number(4),
      PostsAvailable number(4),
  
      constraint GRADE_Grade_CK  check(Grade between 1 and 20),
      constraint GRADE_PostsAvailable_CK check(PostsAvailable &lt;= TotalPosts)
  );
  
  create table EMPLOYEE
  (
      Empno number(4) constraint EMPLOYEE_Empno_PK PRIMARY KEY,
      Name varchar2(10) not null,
      Designation varchar2(50) NOT NULL UNIQUE,
      Qualification varchar2(10),
      Joindate date default sysdate
  
      constraint EMPLOYEE_Designation_FK FOREIGN KEY(Designation) References GRADE(Designation),
  );
  </code></pre>
  
  <p>Now new error</p>
  
  <blockquote>
    <p>constraint EMPLOYEE_Designation_FK FOREIGN KEY(Designation) References GRADE(Designation)
       *</p>
    
    <p>ERROR at line 8:  </p>
    
    <p>ORA-02253: constraint specification not allowed here</p>
  </blockquote>