Configure ou supprime une valeur du registre.

DECLARE
        p_key           alias for $1;
        p_value         alias for $2;
BEGIN
        if p_value is null then
                delete from sl_registry
                                where reg_key = p_key;
        else
                lock table sl_registry;
                update sl_registry
                                set reg_text = p_value
                                where reg_key = p_key;
                if not found then
                        insert into sl_registry (reg_key, reg_text)
                                        values (p_key, p_value);
                end if;
        end if;
        return p_value;
END;