title: Oracle PL/SQL: Calling a procedure from a trigger
body: <p>I get this error when ever I try to fire a trigger after insert on passengers table. this trigger is supposed to call a procedure that takes two parameters of the newly inserted values and based on that it updates another table which is the booking table. however, i am getting this error: </p>
  
  <pre><code>ORA-04091: table AIRLINESYSTEM.PASSENGER is mutating, trigger/function may not see it 
   ORA-06512: at "AIRLINESYSTEM.CALCULATE_FLIGHT_PRICE", line 11 ORA-06512: at 
  "AIRLINESYSTEM.CALCULATE_FLIGHT_PRICE", line 15 ORA-06512: at 
   "AIRLINESYSTEM.CALCULATE_FLIGHT_PRICE_T1", line 3 ORA-04088: error during execution of 
    trigger 'AIRLINESYSTEM.CALCULATE_FLIGHT_PRICE_T1' (Row 3)
  </code></pre>
  
  <p>I complied and tested the procedure in the SQL command line and it works fine. The problem seems to be with the trigger.  This is the trigger code:</p>
  
  <pre><code>create or replace trigger "CALCULATE_FLIGHT_PRICE_T1"
  AFTER
  insert on "PASSENGER"
  for each row
  
  begin
  
  CALCULATE_FLIGHT_PRICE(:NEW.BOOKING_ID);
  
  end;​​​​​
  </code></pre>
  
  <p>Why is the trigger isn't calling the procedure?</p>