OracleDDL,DML,DCL,TCL基础概念Oracle认证考试

文章作者 100test 发表时间 2010:03:07 15:12:21
来源 100Test.Com百考试题网

　　DDL

　　Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:

　　CREATE - to create objects in the database

　　ALTER - alters the structure of the database

　　DROP - 0delete objects from the database

　　TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed

　　COMMENT - add comments to the data dictionary

　　RENAME - rename an object

　　DML

　　Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:

　　SELECT - retrieve data from the a database

　　INSERT - insert data into a table

　　UPDATE - 0updates existing data within a table

　　DELETE - 0deletes all records from a table, the space for the records remain

　　MERGE - UPSERT operation (insert or 0update)