Oracle建表与创建序列详细实例

CREATE TABLE teacher1
(
    id   number,
    name varchar2(32),
    primary key (id)
);
 
select * from teacher1;
 
-- 插入数据
insert into teacher1(id, name) VALUES (7, 'zhangsan');
 
-- 插入数据后确认无误一定要提交，否则不会保存
commit ;
 
-- 修改表名
alter table teacher rename to teacher1;
 
-- 删除表
drop table teacher1;
 
-- 提交事务
commit;

-- 创建序列名称
create sequence teacher_seq;
 
-- 提取下一个值
select teacher_seq.nextval from DUAL;
 
-- 提取当前值
select teacher_seq.currval from DUAL;

-- 先创建表
create table teacher(
    id number,
    name varchar2(32),
    pwd varchar2(32),
    primary key (id)
);
 
-- 再创建序列
create sequence teacher_seq;
 
-- 插入三条数据，将主键id设置为序列的下一个值，这个就相当于自增
insert into teacher values (teacher_seq.nextval,'zs','123');
insert into teacher values (teacher_seq.nextval, 'lx', '456');
insert into teacher(id, name, pwd) values (teacher_seq.nextval, 'ww', '123');
 
-- 插入数据后确认无误一定要提交，否则不会保存
commit ;
 
select * from teacher;

-- 创建序列名称
CREATE SEQUENCE 'sequence_name'
-- 递增`n`的序列（默认：`1`）
-- 如果`n`是正数就递增
-- 如果`n`是负数就递减
[INCREMENT BY 'n']
-- 开始值（递增默认是`minvalue`，递减默认是`maxvalue`）
[START WITH 'n'] 
-- 最大值
[{MAXVALUE 'n' | NOMAXVALUE}]
-- 最小值
[{MINVALUE 'n' | NOMINVALUE}]
-- 循环 | 不循环（默认：`NOCYCLE`）
[{CYCLE | 'NOCYCLE'}] 
-- 分配并存入到内存中（默认：`CACHE`）
[{'CACHE' 'n' | NOCACHE}]; 

-- 创建序列规则是：从100开始，每次+1
create sequence teacher_seq2 start with 100;
select teacher_seq2.nextval from DUAL;
 
-- 创建序列规则是：从5开始到100，超出最大值后无法创建
create sequence teacher_seq3 minvalue 5 maxvalue 100;
select teacher_seq3.nextval from DUAL;
 
-- 创建序列规则是：从1开始，步长为3的方式递增
create sequence teacher_seq4 increment by 3;
select teacher_seq4.nextval from DUAL;
 
-- 创建复杂序列
create sequence teacher_seq5  increment by 4 start with -2 minvalue -2 maxvalue 10;
select teacher_seq5.nextval from DUAL;
 
-- 删除其中一个序列
drop sequence teacher_seq5;

update teacher set pwd='123456' where id = 2;
update teacher set pwd='654321',name='lss' where id = 3;