fix SQL DDL

[Giraudux]

(not tested)

create or replace table Clients ( idcl number       not null,
                                  nom  varchar2(20) not null,
                                  pren varchar2(15) not null,
                                  adr  varchar2(30) not null,
                                  tal  varchar2(12) not null,
                                primary key (idcl) );

create or replace table Livres ( refl   varchar2(10) not null,
                                 titre  varchar2(20) not null,
                                 auteur varchar2(20) not null,
                                 genre  varchar2(15) not null,
                               primary key (refl) );

create or replace table Achats ( idcl      number       not null,
                                 refl      varchar2(10) not null,
                                 dateachat date         not null,
                               primary key (idcl, refl, dateachat),
                               foreign key (idcl) references Clients,
                               foreign key (refl) references Livres );

create or replace table Avis ( idcl number       not null,
                               refl varchar2(10) not null,
                               note number(4,2)  not null,
                               commentaire varchar2(50),
                             primary key (idcl, refl),
                             foreign key (idcl) references Clients,
                             foreign key (refl) references Livres );