title: Oracle 12c: Insert into Table with Identity Column
body: <p>I have a table with one column of type Identity Column, which is also the primary key.</p>
  
  <pre><code>CREATE  TABLE identity_demo  (
      id NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
      description VARCHAR2(100) not null
    );
  </code></pre>
  
  <p>then I insert a few lines of data</p>
  
  <pre><code>insert into identity_demo (id, description) values (1,'A');
  insert into identity_demo (id, description) values (2,'B');
  insert into identity_demo (id, description) values (3,'C');
  insert into identity_demo (id, description) values (4,'D');
  insert into identity_demo (id, description) values (5,'E');
  insert into identity_demo (id, description) values (6,'F');
  </code></pre>
  
  <p>if I now want to insert a row for which the value ID is not set, I get a key violation</p>
  
  <pre><code>insert into identity_demo (description) values ('G');
  </code></pre>
  
  <p>ORA-00001: Unique Constraint (UWE.IDENTITY_DEMO_PK) verletzt
  what's the best way to proceed here?</p>