Store the data of deleted record using trigger - oracle

Question

I want to write a trigger which fires on deletion of a record from a table, and inserts a record in another table and uses the details of the record deleted.
Database : Oracle 10g
My trigger looked like this
CREATE or REPLACE TRIGGER myTrigger
AFTER DELETE
ON myTable
REFERENCING NEW AS old_tab
FOR EACH ROW
BEGIN
INSERT INTO ACTIVITYLOG values ('ADMIN',:old_tab.tabletID,'MIGRATION','ERROR','TEST','T','NIL',sysdate)
END;
here :old_tab.tabletID the tabletID is the column of the table myTable in which deletion is done.
I want to save the I and a log that it was deleted.
But when I try deleting a record I get the following error
Error code 4098, SQL state 42000: ORA-04098: trigger 'DB.MYTRIGGER' is
invalid and failed re-validation
P.S. Ran the trigger creation in NetBeans SQL Editor.
Here is the,
EDIT
STRUCTURE OF myTable (Table deletion occurs)
tabletID varchar2(15) PRIMARY KEY
tabletName varchar2(100)
STRUCTURE OF ACTIVITYLOG
username varchar2(15)
tabletKey varchar2(15)
page_ref varchar2(100)
errors varchar2(100)
remarks varchar2(100)
operationcode char(2)
lastupdateip varchar2(20)
lastupdatedate date
Sorry don't have access to SQL PLUS EDITOR.

Answer 1

You should use the :OLD values rather than the :NEW values. The :NEW values in a DELETE trigger (whether BEFORE or AFTER) are blank. This makes sense, because if you think about it the record has logically ceased to exist at this point.
However that is not a source of compilation errors.
"still the same error shows up on deletion. "
I suppose we could spend all day guessing what's wrong so let's stop now. You can discover the compilation errors with this simple query:
select * from user_errors
where name = 'MYTRIGGER'
and type = 'TRIGGER'
"I changed the :NEW to :OLD, and added a semicolan and ran it on SQL
PLUS, and that did the trick"
For the benefit of future here is a version of the trigger which will compile and which will correctly write the required values:
CREATE or REPLACE TRIGGER myTrigger
AFTER DELETE
ON myTable
REFERENCING OLD AS old_tab
FOR EACH ROW
BEGIN
INSERT INTO ACTIVITYLOG values ('ADMIN',:old_tab.tabletID,'MIGRATION','ERROR','TEST','T','NIL',sysdate);
END;
/

Answer 2

The problem is this:
REFERENCING NEW AS old_tab
You've redefined the NEW values with the label "old_tab". This is somewhat like adding #define FALSE TRUE to the top of a program.
Add a semicolon after the insert statement
Because you're using an AFTER DELETE trigger, you only need to access the :OLD values, e.g.:
CREATE or REPLACE TRIGGER myTrigger
AFTER DELETE
ON myTable
FOR EACH ROW
BEGIN
INSERT INTO ACTIVITYLOG values ('ADMIN',:OLD.tabletID,'MIGRATION','ERROR','TEST','T','NIL',sysdate);
END;