title: Oracle trigger to create an autonumber
body: <p>I have never created a trigger in Oracle before so I am looking for some direction.</p>
  
  <p>I would like to create a trigger that increments an ID by one if the ID isnt in the insert statement.  </p>
  
  <p>The ID should start at 10000, and when a record is inserted the next ID should be 10001.  If the insert statement contains a ID, it should override the auto increment.</p>
  
  <p>ie</p>
  
  <pre><code>insert into t1 (firstname, lastname) values ('Michael','Jordan'),('Larry','Bird')
  </code></pre>
  
  <p>should look like:</p>
  
  <p>firstname    lastname    id</p>
  
  <p>Micahel      Jordan      10000</p>
  
  <p>Larry        Bird        10001</p>
  
  <pre><code>insert into t1 (firstname, lastname, id) values ('Scottie','Pippen',50000)
  </code></pre>
  
  <p>should look like:</p>
  
  <p>firstname    lastname    id</p>
  
  <p>Micahel      Jordan      10000</p>
  
  <p>Larry        Bird        10001</p>
  
  <p>Scottie      Pippen      50000</p>