Oracle数据库---序列、索引、同义词

--创建序列
create sequence deptno_seq
start with 50
increment by 10
maxvalue 70
cache 3;

--为了方便演示，创建了一个和dept表结构相同的deptnew表
create table deptnew
as
select * from dept;

--向表中插入数据，并通过序列给主键列deptno提供数据
insert into deptnew(deptno,dname,loc)values(deptno_seq.nextval,'test_dname','test_loc');
select * from deptnew;

--currval
select deptno_seq.currval from dual;

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

--向数据库提交插入的数据
commit;

--修改序列
alter sequence deptno_seq
maxvalue 90;

--测试
insert into deptnew(deptno,dname,loc)values(deptno_seq.nextval,'test_dname','test_loc');
select * from deptnew;
rollback;
insert into deptnew(deptno,dname,loc)values(deptno_seq.nextval,'test_dname','test_loc');
select * from deptnew;
commit;

--删除序列
drop sequence deptno_seq;

--创建单列索引
create index idx_ename on emp(ename);

--创建复合索引
create index idx_deptno_job on emp(deptno,job);

--创建唯一索引
create unique index idx_dname on dept(dname);

--创建非唯一索引
create index idx_job on emp(job);

--查询索引
select uic.index_name, uic.column_name, uic.column_position, ui.uniqueness
from user_indexes ui, user_ind_columns uic
where uic.index_name = ui.index_name and ui.table_name='EMP';

--删除索引
drop index idx_dname;

--system用户的演示代码

--给scott用户授予创建公共同义词的权限
grant create public synonym to scott;

--给scott用户授予创建私有同义词的权限
grant create synonym to scott;

--测试
--使用scott用户下的私有同义词
select * from scott.en;

--使用scott用户下的公共同义词
select * from dn;

--给scott用户授予删除公共同义词的权限
grant drop public synonym to scott;

--scott用户的演示代码

--创建公共同义词
create public synonym dn for scott.deptnew;

--使用公共同义词
select * from dn;

--创建私有同义词
create synonym en for scott.empnew;

--使用私有同义词
select * from en;

--查看私有同义词
select synonym_name,table_owner,table_name
from syn
where synonym_name = 'EN';

--查看公共同义词
select synonym_name,table_owner,table_name
from all_synonyms
where synonym_name = 'DN';

--删除公共同义词
drop public synonym dn;

--删除私有同义词
drop synonym en;

 

转载于:https://www.cnblogs.com/xiaomifeng1010/p/11111965.html