Oracle to create tables, delete tables, modify the table (add fields, change fields, remove fields) statement summary

Oracle to create the table:

　　create table 表名 (

　　　　Field Name Field Type 1 if the default value is empty,

　　　　Field Name Field Type 2 if the default value is empty,

　　　　Field Name Field Type 3 if the default value is empty,

　　　　......

　　);

　　Create a user table:

　　create table user (

　　　　id number(6) primary key,  ---主键

　　　　name varchar (50) not null, --- name is not null

　　　　sex varchar2 (6) default 'male' check (sex in ( 'male', 'female')) --- sex default 'male'

　　);

Modify the table name:

　　rename the old table to the new table name;

　　rename user to newuser;

Oracle delete table:

　　delete from 表名；

　　Delete to delete the data is a one of the deleted data, where conditions can be added later, without deleting the table structure. Note: If the table has generated identity increment id column, after delete from still increased from the previous number.

　　truncate table 表名；

　　truncate disposable delete all data, without deleting the table structure. Note: If the table has generated identity increment id column, after truncate, will restore the original value.

　　drop table 表名；

　　drop delete all data will be deleted table structure.

Oracle modify the table:

　　Add new field:

　　alter table table add (Type Default Value field name field is empty);

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

　　alter table user add (course varchar2(30) default '空' not null);

　　Modify the field:

　　alter table table name modify (Field Type Default name field is blank);

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

　　Modify field names:

　　alter table table name rename column column column name to the new name;

　　alter table user rename column course to newcourse;

　　Delete field:

　　alter table drop column table name field name;

　　alter table user drop column course;