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Oracle创建表语句介绍

2024-07-03 | 佚名 | 点击:

oracle 创建表时,表名称会自动转换成大写,oracle 对表名称的大小写不敏感。

oracle 表命名规则:

二、语法

2.1 创建表 create table

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-- 创建表: student_info 属主: scott (默认当前用户)

 

create table scott.student_info (

  sno         number(10) constraint pk_si_sno primary key,

  sname       varchar2(10),

  sex         varchar2(2),

  create_date date

);

 

-- 添加注释

comment on table scott.student_info is '学生信息表';

comment on column scott.student_info.sno is '学号';

comment on column scott.student_info.sname is '姓名';

comment on column scott.student_info.sex is '性别';

comment on column scott.student_info.create_date is '创建日期';

 

-- 语句授权,如:给 hr 用户下列权限

grant select, insert, update, delete on scott.student_info to hr;

插入验证数据:

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-- 插入数据

insert into scott.student_info (sno, sname, sex, create_date)

values (1, '张三', '男', sysdate);

insert into scott.student_info (sno, sname, sex, create_date)

values (2, '李四', '女', sysdate);

insert into scott.student_info (sno, sname, sex, create_date)

values (3, '王五', '男', sysdate);

 

-- 修改

update scott.student_info si

   set si.sex = '女'

 where si.sno = 3;

  

-- 删除

delete scott.student_info si where si.sno = 1;

 

-- 提交

commit;

 

-- 查询

select * from scott.student_info;

2.2 修改表 alter table

1. '增加' 一列或者多列

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alter table scott.student_info add address varchar2(50);

alter table scott.student_info add (id_type varchar2(2), id_no varchar2(10));

2. '修改' 一列或者多列

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alter table scott.student_info modify address varchar2(100);

alter table scott.student_info modify (id_type varchar(20), id_no varchar2(20));

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alter table scott.student_info rename column address to new_address;

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alter table scott.student_info rename to new_student_info ;

alter table scott.new_student_info rename to student_info;

3. '删除' 一列或者多列,删除多列时,不需要关键字 column

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alter table scott.student_info drop column sex;

alter table scott.student_info drop (id_type, id_no);

2.3 删除表 drop table

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-- 删除表结构

drop table scott.student_info;

2.4 清空表 truncate table

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-- 清空表数据

truncate table scott.student_info;

2.5 查询表、列、备注信息

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'dba_xx' > all_xx > user_xx ('dba_xx' DBA 用户才有权限)

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select * from dba_tables; -- all_tables、user_tables

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select * from dba_tab_comments;

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select * from dba_tab_cols t order by t.column_id;

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select * from dba_col_comments;

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