ORACLE trigger example

Create Or Replace Trigger Usertotemp after Insert Or Update Or Delete
On T_cs_one For Each row
Declare
Integrity_error exception;
Errno Integer ;
Errmsg Char ( 200 );
Tem1 Varchar2 ( 10 );

Begin

If Inserting Then
Select Count (MC2) Into Tem1 From T_cs_two Where MC2 = : New. mc1; // set
If Tem1 <= 0 Then
Insert Into T_cs_two (MC2) Values (: New. mc1 );
End If ;
Elsif updating Then
Update T_cs_two Set MC2 = : New. mc1 Where MC2 = : Old. mc1;
Elsif deleting Then
Delete From T_cs_two Where MC2 = : Old. mc1;
End If ;
Exception
When Integrity_error Then
Raise_application_error (errno, errmsg );
End ;