Problem with postgreSQL triggers

Hello,
I have some trouble with postgresql triggers: 
I just want to execute an sql query (insert) in a trigger and I don't manage to
write the corresponding procedure.
Is it possible to use the traditionnal structure:               create trigger <trigger name>              before
deleteon <table name>              for each row              BEGIN              query;              END;    ?
 
Otherwise, how can I deal with the "execute procedure <procedure name>"
statement?
Thanks

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S�bastien BOUTELOUP
stagiaire � l'UFR DGES
�l�ve ing�nieur 2�me ann�e ENSIMAG

t�l: 04.76.51.49.61