Oracle create table, delete table, modify table (add field, modify field, delete field) statement summary

Create table ：

create table Table name (

Field name 1 Field type The default value is Is it empty ,

Field name 2 Field type The default value is Is it empty ,

Field name 3 Field type The default value is Is it empty ,

…

);

Create a user surface ：

create table user (

id number(6) primary key, — Primary key

name varchar(50) not null, — full name Not for null

sex varchar2(6) default ‘ male ’ check ( sex in (‘ male ’,‘ Woman ’)) — Gender Default ’ male ’

);

Modify the name of the table ：

rename The old name of the table to The new name of the table ;

rename user to newuser;

Delete table ：

delete from Table name ;

delete Deleting data is deleting data one by one , You can add where Conditions , Do not delete table structure . Be careful ： If there is identity The resulting self accretion id Column ,delete from After that, it still increased from the last number .

truncate table Table name ;

truncate Delete all data at once , Do not delete table structure . Be careful ： If there is identity The resulting self accretion id Column ,truncate after , Will restore the initial value .

drop table Table name ;

drop Delete all data , The table structure will be deleted .

Modify table ：

Add new fields ：

alter table Table name add( Field name Field type The default value is Is it empty );

alter table user add(age number(6) null);

alter table user add (course varchar2(30) default ‘ empty ’ not null);
　　
alter table user add create_date date null;
Add a comment to the field ：comment on column table.create_date is ‘ Date of creation ’;

Modify fields ：

alter table Table name modify ( Field name Field type The default value is Is it empty );

alter table user modify(age number(8));

Modify field name ：

alter table Table name rename column Name to New column names ;

alter table user rename column course to newcourse;

Delete field ：

alter table Table name drop column Field name ;

alter table user drop column course;