DDL, DML, DCL

DDL (data definition Language): Database definition language < NOTE keyword table>

　　1, create table table_name ()

　　2, alert table table_name

(1). Add columns
An example of the complete definition of the ALTER table tb_name add column: Alter TABLE S_stu Add (sname varchar2 (), sage number);

(2). Delete a column
Alter table tb_name drop column col_name;

(3). Modifying column properties (data types and constraints)
An example of the complete definition of the ALTER table tb_name modify column: ALTER TABLE S_STU modify sname varchar (10);
　　3, drop table tb_name [cascade constraint];

　　4, truncate table tb_name

DML (Data Manipulation Language): Database manipulation language

　　1, INSERT INTO table_name (...) VALUES (...)

　2,update table_name SET column_name =, where,,,

　　3,Delete from table_name where,,,

DCL (Data Control Language): Controls statements

Grant Authorization
REVOKE Cancel Authorization

DDL, DML, DCL