title: ORACLE "before update" trigger does not fire when column is changed within another trigger
body: <p>I am using ORACLE 12c.</p>
  
  <p>On a table I have 2 triggers, both "before update". 
  One of the triggers fires while updating a column and within this trigger another column gets a new value. The second trigger should fire while updating this second column. But he did not.</p>
  
  <pre><code>create table TRIGGER_TEST
  (
      col1 varchar2(64),
      col2 varchar2(64),
      col3 varchar2(64)
  );
  
  create or replace trigger TR_TRIGGER_TEST_1 
  before update of COL1 on TRIGGER_TEST
  for each row
  begin
      dbms_output.put_line('here we are in TR_TRIGGER_TEST_1');
      :new.col2 := 'only testing';
  end;
  /
  
  create or replace trigger TR_TRIGGER_TEST_2
  before update of COL2 on TRIGGER_TEST
  for each row
  begin
      dbms_output.put_line('here we are in TR_TRIGGER_TEST_2');
      :new.col3 := 'trigger_test_2 has fired';
  end;
  /
  
  
  insert into TRIGGER_TEST values ('1_col1','1_col2','1_col3');
  select * from TRIGGER_TEST;
  
  COL1                 COL2              COL3                                                    
  ----------------------------------------------------------------
  1_col1               1_col2            1_col3                                                          
  </code></pre>
  
  <p>After I have inserted the row I perform an UPDATE. And I expect COL1=
  "now we will see", COL2="only testing" and COL3 = "trigger_test_2 has fired".</p>
  
  <pre><code>update TRIGGER_TEST set COL1 = 'now we will see';
  </code></pre>
  
  <p>But what I get is this:</p>
  
  <pre><code>select * from TRIGGER_TEST;
  
  
  COL1                 COL2              COL3                                                    
  ----------------------------------------------------------------
  now we will see      only testing      1_col3                                                          
  </code></pre>
  
  <p>Can anybody explain this to me? I am really sure, that with former ORACLE versions this szenario has worked. But now it does not.</p>