[bbk5123] 第101集 -第12章 -数据移植 07

Oracle 数据引擎

ORACLE_LOADER 用户只能从外部读取表数据，但是不能将数据库中的数据卸载到操作系统文件中.

ORACLE_DATAPUMP 用户不仅可以从外部表中读取数据，同时可以将数据库中复杂的数据查询后卸载到操作系统文件中.

External Tables

External tables are read-only tables stored as files on the operating outside of the Oracle database.

External Table Benefits

Data can be used directly from the external file or loaded into another database.

External data can be queried and joined directly in parallel with tables residing in the databas ,without requiring it to be loaded first.

The results of a complex query can be unloaded to an external file.

You can combine generated files from different sources for loading purposes.

Defining an External Tables with ORACLE_LOADER

External Table Population with ORACLE_DATAPUMP

Using External Tables

Querying and external table:

SQL>SELECT * FROM extab_employees;

Querying and joining an external table with an internal table

SQL>SELECT e.employee_id,e.first_name,e.last_name,d.department_name

FROM departments d,extab_employees e

WHERE d.department_id = e.department_id;

Appending data to an internal table from an external table

SQL>INSERT /*+ APPEND*/ INTO hr.employees SELECT * FROM extab_employees;

Summary

In this lesson,you should have learned how to:

Describe ways to move data

DATA PUMP

SQL LOADER

EXTERNAL TABLE

Use SQL*Loader to load data from a non-Oracle database (or user files)

Use external tables to move data via platform-independent files

Explain the general architecture of Oracle Data Pump

Use Data Pump Export and Import to move data between Oracle databases.