how to create trigger

**TABLE TRIGGER
We can express a trigger creater code as a general aspect;

CREATE [OR REPLACE] TRIGGER trig_name
{BEFORE|AFTER} {DELETE OR INSERT OR UPDATE}
[OF column_name] ON table_name
[FOR EACH ROW]
DECLARE
--variables
BEGIN
--some code
END;


Brackets represents optionality and “|” means “OR”.

sqlplus error viewing

while creating a function or a procedure if we get compile errors from sqlplus,
after the error line, we should write this piece of code to get information about errors;
show errors