title: SQL Error: ORA-02000: missing ALWAYS keyword when create identity column based table
body: <p>I try to create an auto incremented column on a table and as I see in this <a href="https://stackoverflow.com/questions/11296361/how-to-create-id-with-auto-increment-on-oracle">post</a> there are 2 ways, the second implementation with the Identity column is a more elegant solution, but when I try to implement it I get the following error:</p>
  
  <pre><code>    Error at Command Line : 3 Column : 31
      Error report -
      SQL Error: ORA-02000: missing ALWAYS keyword
      02000. 00000 -  "missing %s keyword"
  </code></pre>
  
  <p>Actual table script implementation:</p>
  
  <pre><code>CREATE TABLE "PLATFORM"."AUTH_PERMISSION"
  (
      ID NUMBER(19,0) GENERATED BY DEFAULT ON NULL AS IDENTITY, 
      -- ID NUMBER(19,0) PRIMARY KEY NOT NULL,
      NAME VARCHAR2(50) UNIQUE NOT NULL,
      ACTION_ID NUMBER(19,0) NOT NULL,
      RESOURCE_ID NUMBER(19,0) NOT NULL,
      ENVIRONMENT_ID NUMBER(19,0) NOT NULL,
      CONSTRAINT "ACTION_ID" FOREIGN KEY ("ACTION_ID")
        REFERENCES "AUTH_ACTION" ("ID") ENABLE,
      CONSTRAINT "ENVIRONMENT_ID" FOREIGN KEY ("ENVIRONMENT_ID")
        REFERENCES "AUTH_ENVIRONMENT" ("ID") ENABLE,
      CONSTRAINT "RESOURCE_ID" FOREIGN KEY ("RESOURCE_ID")
        REFERENCES "AUTH_RESOURCE" ("ID") ENABLE,
      UNIQUE (ACTION_ID, ENVIRONMENT_ID, RESOURCE_ID)
  );
  </code></pre>
  
  <p>It can bee seen that the column that I try to auto-increment is the primary key of the table. </p>
  
  <p><a href="http://docs.oracle.com/database/121/DRDAA/migr_tools_feat.htm#DRDAA109" rel="noreferrer">This</a> is the reference from where I got the solution.</p>
  
  <p>The problem was that I used an older version of Oracle, 11g.</p>