Orcale笔记

创建表

create table 表名
(
    列名 类型 描述,
    列名 类型 描述
);

例如：

create table StuInfo
(
    stuno number not null,
    stuname varchar2(20) not null
);

删除表

drop table StuInfo;

查看表结构

desc StuInfo;

查看所有表

desc user_tables;
select table_name from user_tables;

禁用/启用账号 tiger

alter user scott acount lock;
alter user scott acount unlock;

修改账号密码

alter user scott identified by 新密码;

登录状态下切换账户

conn 账户/密码;
conn sys/123456 as sysdba;
conn system/123456;
conn scott/123456;

创建StuInfo表

create table StuInfo
(
    stuno number not null,
    stuname nvarchar2(10) not null,
    stuage number not null,
    stuid char(18) null,
    stuseat number not null,
);

查询无重复的行

select distinct stuname from stuinfo;
select distinct stuname,stuage from stuinfo;

排序

select * from stuinfo
order by stuage desc, stuno desc;

列别名

select
  stuno as "学号",
  stuname as "姓名",
  stuage as "年龄"
from stuinfo;

将数据导入现有表

insert into Table2(a, c, d) 
select a,c,5 from Table1;

将数据导出到新表

create table Table2 
as 
    select a,c from Table1;

导出表结构（导出不带数据的表）

select a,c into Table2 from Table1
where 1=2;

聚合函数

1. count()
2. sum()
3. max()
4. min()
5. avg()

select avg(stuage) from stuinfo;

事务操作

insert into stuinfo(stuno, stuname, stuage, stuid, stuseat) values(6, '小明', 18, '12345678', 1);
insert into stuinfo(stuno, stuname, stuage, stuid, stuseat) values(7, '小明', 18, '12345678', 1);
savepoint a;
insert into stuinfo(stuno, stuname, stuage, stuid, stuseat) values(8, '小明', 18, '12345678', 1);
rollback to savepoint a;
insert into stuinfo(stuno, stuname, stuage, stuid, stuseat) values(9, '小明', 18, '12345678', 1);
commit;