序列

--create sequence

create sequence empseq
increment by 10
start with 10
maxvalue 100
cycle--need cycle
nocache--needn't cache


--查询序列
select sequence_name,min_value,max_value,increment_by,last_number 
from user_sequences


--查找下一个值
select empseq.nextval from dual
--查找当前值
select empseq.currval from dual

--修改序列[不能更改启动序列号]
alter sequence empseq
increment by 1
nocycle
nocache

--删除序列

--使用序列作为主键向表中插入值
insert into emp01
values(empseq.nextval,'AA',5500)

索引和同义词

--创建索引 create index emp01_id_ix on emp01(employee_id) --删除索引 drop index emp01_id_ix; --创建同义词； create synonym e for employees select * from e --删除同义词 drop synonym e;