title: How can same foreign key have multiple references in SQL?
body: <p>I'm trying to take the relationary representation to SQL but I get the following error (my sql then error)</p>
  
  <pre><code>CREATE TABLE REQUISITION
  (REQNO CHAR(6) CONSTRAINT REQNO_PK PRIMARY KEY,
  STAFFNO REFERENCES STAFF_CHARGENURSE(STAFFNO),
  STAFFNAME REFERENCES SUPPLIES_PHARMACEUTICAL(STAFFNAME),
  STAFFNAME REFERENCES SUPPLIES_SURGICAL(STAFFNAME),
  STAFFNAME REFERENCES SUPPLIES_NON-SURGICAL(STAFFNAME),
  WARDNO CHAR(6),
  ITEMNO CHAR(6),
  QUANTITY INT,
  DATEORDERED DATE,
  DATERECIEVED DATE);
  </code></pre>
  
  <hr>
  
  <pre><code>STAFFNAME REFERENCES SUPPLIES_SURGICAL(STAFFNAME),
  *
  ERROR at line 5: 
  ORA-00957: duplicate column name
  </code></pre>
  
  <p>How do I enter more than one foreign key in SQL? All itemNo's point back to a superclass in a MANDATORY, OR relationship which is why they're 3 instances of itemNo as a foreign key. Relationary:</p>
  
  <pre><code>Requisition(reqNo, staffNo, staffName, wardNo, itemNo, quantity, dateOrdered, dateRecieved)
      Primary Key reqNo
      Foreign Key staffNo references Staff_ChargeNurse(staffNo)
      Foreign Key itemNo references Supplies_Pharmaceutical(itemNo)
      Foreign Key itemNo references Supplies_Surgical(itemNo)
      Foreign Key itemNo references Supplies_Non-Surgical(itemNo)
  </code></pre>