title: Cannot insert NULL into, ERROR during execution of trigger
body: <p>I have created a Trigger on table Customers so that every time a record is deleted from table customers this same record is inserted in table Customer_Archives with the current date as Deletion_Date.</p>
  
  <p>I am have to insert a new customer into table Customers and then delete it. The record must be inserted correctly into table Customers_Archive.</p>
  
  <p>Here's script I have so far:</p>
  
  <pre><code>CREATE TABLE Customer_Archives
  (
    customer_id           NUMBER          NOT NULL,
    customer_first_name   VARCHAR2(50),
    customer_last_name    VARCHAR2(50)    NOT NULL,
    customer_address      VARCHAR2(255)   NOT NULL,
    customer_city         VARCHAR2(50)    NOT NULL,
    customer_state        CHAR(2)         NOT NULL,
    customer_zip          VARCHAR2(20)    NOT NULL,
    customer_phone        VARCHAR2(30)    NOT NULL,
    customer_fax          VARCHAR2(30),
    deletion_date         DATE, 
    CONSTRAINT customer_archives_pk 
      PRIMARY KEY (customer_id)
  );
  
  CREATE OR REPLACE TRIGGER Customers_before_insert
  BEFORE DELETE ON Customers
  FOR EACH ROW 
  DECLARE 
      ar_row Customers%rowtype;
  BEGIN
  INSERT INTO Customer_Archives 
  VALUES(ar_row.Customer_id,
      ar_row.Customer_First_Name,
      ar_row.Customer_Last_Name,
      ar_row.Customer_Address,
      ar_row.Customer_City,
      ar_row.Customer_State,
      ar_row.Customer_Zip,
      ar_row.Customer_Phone,
      ar_row.Customer_Fax, 
      sysdate());
      dbms_output.put_line('New row is added to Customers_Archive 
      Table with Customer_ID:' ||ar_row.Customer_id ||'on date:' || sysdate());
  END;
  /
  
  SELECT trigger_name, status FROM user_triggers;
  
  INSERT INTO CUSTOMERS
  (customer_id, customer_first_name, customer_last_name, customer_address, 
  customer_city, customer_state, customer_zip, customer_phone, customer_fax)
  VALUES (27,'Sofia','Chen','8888 Cowden St.','Philadelphia','PA',
  '19149',7654321234',NULL);
  
  DELETE FROM CUSTOMERS
  WHERE customer_id = 27;
  </code></pre>
  
  <p>When I try to delete the customer that I just inserted I get an error:</p>
  
  <pre><code>Error starting at line : 47 in command -
  DELETE FROM CUSTOMERS
  WHERE customer_id = 27
  Error report -
  ORA-01400: cannot insert NULL into ("TUG81959"."CUSTOMER_ARCHIVES"."CUSTOMER_ID")
  ORA-06512: at "TUG81959.CUSTOMERS_BEFORE_INSERT", line 4
  ORA-04088: error during execution of trigger 'TUG81959.CUSTOMERS_BEFORE_INSERT'
  </code></pre>