序列创建：
create sequence seq_patientid
increment by 1
start with 1
maxvalue 9999999999999999999999999999
cycle
nocache;
序列使用：
seq_patientid.nextval
序列创建：
create sequence seq_patientid
increment by 1
start with 1
maxvalue 9999999999999999999999999999
cycle
nocache;
序列使用：
seq_patientid.nextval