Procedure needed 4 changing the sequence order

Question

For example, there are ten employees. The first employee’s id will be 1. The second employee says his id he wants to be 14. For the third employee, the employee id should come in sequence, i.e it should assign 2 by default, if he have not requested an id. Again when the fourth employee comes, he will request for number 4. When fifth employee comes, he will be assigned number 3, when he has not requested of his choice. When sixth employee comes, number 5 should be assigned, since number 4 is already in use.
So how can I write a Procedure for this?

Answer 1

this example might be of help.
  -- assuming that you have this in your procedure:
  -- pEmpId Number        => for Employee ID
  -- vEmpId Number        => place holder for employee id
  -- vCtr   Number        => counter for checking rows
  -- emp_seq_no           => sequence for employee
  -- employee does not request for an Id
  If pEmpId Is Null Then
    Loop
      Select emp_seq_no.nextval
        Into vEmpId
        From dual;
      --check if existing on the table
      Select empid
        Into vCtr1
        From employee
       Where empid = vEmpId; 
      If vEmpId <> vCtr1 Then
        exit;
      End If
    End Loop;
  Else
    -- employee requested for an Id
    Select Count(*)
      Into vCtr1
      From employee
     Where empid = vEmpId; 
    -- check if existing on the table
    If vCtr1 > 0 Then
      -- code goes here on what do you want to do when
      -- the requested id exists
    End If;
  End If;note: this code has not been tested.