CREATE type recommendation as object(
    descriptions varchar2(200)
);

create type recomand as table of recommendation;


create type traitement_type as object (
id_traitement number(7),
    duree varchar2(25),
    recome recomand,
    description varchar2(250)
    
);

CREATE TABLE Traitement (primary key(id_traitement))
nested table recome store as Les_recommendations;

我执行这些命令，在最后一次查询时收到错误：
ORA-00904：：无效标识符
有什么解决办法吗？