This is the trigger:

create trigger T_Noleggio
after insert on Noleggio
for each row
begin
IF((:new.codcliente=prenotazione.codcliente)&&(:ne w.codfilm=prenotazione.codfilm)
&&(:new.codnegozio=prenotazione.codnegozio)
delete prenotazione
end

what's the problem??
Thank, you Elisa

The table Prenotazione is:
CREATE TABLE Prenotazione
(CodFilm NUMBER(10) NOT NULL,
CodNegozio NUMBER(10) NOT NULL,
CodCliente VARCHAR(10) NOT NULL,
Data_Prenotazione date NOT NULL,
Supporto VARCHAR2(3) NOT NULL,
PRIMARY KEY(CodFilm,CodNegozio,CodCliente,Data_Prenotazion e),
FOREIGN KEY(CodNegozio)
REFERENCES Negozio(IdNegozio)
ON DELETE CASCADE,
FOREIGN KEY(CodFilm)
REFERENCES Film(IdFilm)
ON DELETE CASCADE,
FOREIGN KEY(CodCliente)
REFERENCES Cliente(User_id)
ON DELETE CASCADE)

and the table noleggio is:

CREATE TABLE Noleggio
(CodFilm NUMBER(10) NOT NULL,
CodNegozio NUMBER(10) NOT NULL,
CodCliente VARCHAR(10) NOT NULL,
Data_Noleggio date NOT NULL,
Supporto VARCHAR2(3) NOT NULL,
PRIMARY KEY(CodFilm,CodNegozio,CodCliente,Data_Noleggio),
FOREIGN KEY(CodNegozio)
REFERENCES Negozio(IdNegozio)
ON DELETE CASCADE,
FOREIGN KEY(CodFilm)
REFERENCES Film(IdFilm)
ON DELETE CASCADE,
FOREIGN KEY(CodCliente)
REFERENCES Cliente(User_id)
ON DELETE CASCADE)

Elisa,

You are trying to compare values passed to the trigger by insert statement with the values from anothe table without retrieving those values from the table.
How this poor trigger should know what is the value of for example prenotazione.codcliente ?

Hope it explains it,

Jacek

The value of prenotazione.codcliente is carchar2, while the value of prenotazione.idfilm nd prenotazione.ifnegozio is number.
Thank you Elisa

As far as I understand what you are trying to do trigger should look something like that:

create trigger T_Noleggio
after insert on Noleggio
for each row
begin
delete from prenotazione where
codcliente =:new.codcliente and
codfilm=:new.codfilm and
codnegozio=:new.codnegozio;
end;

It will delete from prenotazione row with matching new values.

Hope it helps,

Jacek

thank you for your help but when I do an insert on noleggio the result is:
Error: ORA-04098: trigger 'T_NOLEGGIO' is invalid and failed re-validation

The problem is this I've two table prenotazione and noleggio with the same field but when I insert a new value on noleggio I check if the value is on the table prenotazione and if there is I want to delete.
What's the trigger that resolv this problem?
Thank you
Elisa

I've just resolv the problem ... I bad write the trigger.
Elisa