title: .nextval JDBC insert problem
body: <p>I try to insert into table with sequence .nextval as primary key, the sql in Java is </p>
  
  <pre><code>sql = "INSERT INTO USER 
           (USER_PK, ACCOUNTNUMBER, FIRSTNAME, LASTNAME, EMAIL ) 
         VALUES 
           (?,?,?,?,?)";
     ps = conn.prepareStatement(sql);
     ps.setString(1, "User.nextval");
     ps.setString(2, accountNumber);
     ps.setString(3, firstName);
     ps.setString(4, lastName);
     ps.setString(5, email);
  </code></pre>
  
  <p>However, the error is <code>ORA-01722: invalid number</code></p>
  
  <p>All the other fields are correct, I think it is the problem of sequence, is this correct?</p>