原因：不同于mysql,Oracle数据库在添加表字段时不能直接用comment，而是单独写一个sql语句，如下：

alter table SYS_USER add SENDMSG_LASTTIME date;
comment on column SYS_USER.SENDMSG_LASTTIME is '上一次发送短信时间';

alter table B_PREPARE_INFO add (spec VARCHAR2(20) ,total_packages VARCHAR2(20),net_weight VARCHAR2(20));
comment on column B_PREPARE_INFO.spec is '规格';
comment on column B_PREPARE_INFO.total_packages is '总件数';
comment on column B_PREPARE_INFO.net_weight is '净重';