--查询当前值
select seq_test.nextval from dual; ----修改序列为增加的步长为50
alter sequence seq_test increment by 50 nocache;  
---获取调整后的下一个值
select seq_test.nextval from dual;         
----修改序列为原来的规则
alter sequence seq_test increment by 1;      ---获取调整后下一个数值
select seq_test.nextval from dual;