Syntax to write a Trigger

SYNTAX to WRITE a TRIGGER:

Create or Replace Trigger[schema] Trigger_name
{before or after}
{delete,insert,update[of column...]}
ON [schema.] table_name
[referencing {OLD[as]old} {NEW[as]new}]
[for each row[when search_condition]]
Declare 
declaration of variables;
Begin
statement1;
.
.
statement n;
Exception
Exception handling statements;
End;