SQL Delete trigger for multiple table - sql

Question

So I have two table with id_pastille and I want to create a trigger that each time that one id_pastille is deleted every table that has the id_pastille is deleted as well.
CREATE TABLE tp1_trajet
(
id_trajet int NOT NULL,
longitude double precision NOT NULL,
latitude double precision NOT NULL,
"date" timestamp NOT NULL,
id_pastille int NOT NULL,
CONSTRAINT PK_zone_geographique PRIMARY KEY ( id_trajet ),
CONSTRAINT FK_ FOREIGN KEY ( id_pastille ) REFERENCES tp1_pastille ( id_pastille )
and let say this table
CREATE TABLE tp1_compte
(
id_compte int NOT NULL,
date_achat date NOT NULL,
id_pastille int NOT NULL,
id_usager int NOT NULL,
probabilite_malade double precision NULL,
CONSTRAINT PK_compte PRIMARY KEY ( id_compte ),
CONSTRAINT UQ_compte_id_pastille UNIQUE ( id_pastille ),
CONSTRAINT UQ_compte_id_usager UNIQUE ( id_usager ),
CONSTRAINT FK_compte_id_pastille FOREIGN KEY ( id_pastille ) REFERENCES tp1_pastille ( id_pastille ),
CONSTRAINT FK_compte_id_usager FOREIGN KEY ( id_usager ) REFERENCES tp1_usager ( id_usager )
);
I came up with this so far :
CREATE FUNCTION Delete_pastille() RETURNS trigger
AS $DeleteCustomerWithOrders$
BEGIN
DELETE FROM tp1_bulle,
tp1_compte,
tp1_pastille,
tp1_signes_vitaux,
tp1_usager,
tp1_transaction,
tp1_trajet
WHERE id_pastille = OLD."Id";
RETURN OLD;
END;
$DeleteCustomerWithOrders$
LANGUAGE plpgsql;

Answer 1

You can only delete from a single table in a DELETE statement. Try using several statements.
The best solution might be to define foreign key constraints on all but one of these columns that point to the table that contains the original copy (pastille?). If the foreign key is defined with ON DELETE CASCADE, deleting the original will automatically delete all the dependent rows.

Answer 2

alter table tp1_trajet
drop constraint fK_,
add constraint fK_
foreign key (ID_pastille)
references tp1_pastille (ID_pastille)
on delete cascade;
alter table tp1_compte
drop constraint FK_compte_id_pastille,
add constraint FK_compte_id_pastille
foreign key (ID_pastille)
references tp1_pastille (ID_pastille)
on delete cascade;