Data Base-Oracle 10g

很多年前,學生時代學校是教Dbase, 過去職場工作公司的ERP 是用關聯式資料庫, 原理是一樣的.
Oracle 10-g 就是 relational DB.

關聯式資料庫
優點也是缺點就是它的嚴謹與正規化, 資料的每一個欄位與屬性都要先規劃好.

實體關係模型 (entity- relation model)
很適合文組背景的人去學,  多去找一些真實生活中的資料庫應用場景, 把行業需求做成關聯模型.

練習  ER model 轉成 關聯表

關聯式資料庫- relational DB, 就是有很多TABLE. 很多表格.  表格之間都有鍵值相關 把每個表關聯起來,   生活裡已有很多應用場景, 像身分證, 健保卡,駕照, 行照, 會員卡. 應用無所不在.

資料型態

DB 有分:

階層式: PCR type (parent-child relationship type)

網路式: 多對多

關聯式

db 的重點:功能相依
儲存方面:

Storage

in the form of tablespaces
Tablespaces can contain various types of memory segments, such as Data Segments, Index Segments, etc. Segments in turn comprise one or more extents. Extents comprise groups of contiguous data blocks. Data blocks form the basic units of data storage.

A DBA can impose maximum quotas on storage per user within each tablespace.[9]

-分割

The partitioning feature was introduced in Oracle 8
This allows the partitioning of tables based on different set of keys (鍵).
Specific partitions can then be easily added or dropped to help manage large data sets.

-監看
Monitoring

Oracle database management tracks its computer data storage with the help of information stored in the SYSTEM tablespace.

The SYSTEM tablespace contains the data dictionary—and often (by default) indexes and clusters.

A data dictionary consists of a special collection of tables that contains information about all user-objects in the database. Since version 8i, the Oracle RDBMS also supports “locally managed" tablespaces that store space management information in bitmaps in their own headers rather than in the SYSTEM tablespace (as happens with the default “dictionary-managed" tablespaces). Version 10g and later introduced the SYSAUX tablespace, which contains some of the tables formerly stored in the SYSTEM tablespace, along with objects for other tools such as OEM, which previously required its own tablespace.

現在資料的形式越來越多元, 有時結構化的資料庫太嚴謹不方便.

用哪一種資料庫, 還是要從需求面及對技術的熟悉度, 成本, 安全性來考慮.

對創業而言,成本是一大考量,  成本減少,效益才看得出來.

學資料庫的搜尋和分析, 對數字管理有很大幫助.
這關聯式資料庫發展有10多年了吧,  雖然不是新的,但很實用,  理解資料庫的原理和實際場景的建模, 其他的資料庫道理是一樣的.

(閱讀: Oracle data base : https://en.wikipedia.org/wiki/Oracle_Database)

Advertisements
新文章
發表留言

發表迴響

在下方填入你的資料或按右方圖示以社群網站登入:

WordPress.com Logo

您的留言將使用 WordPress.com 帳號。 登出 / 變更 )

Twitter picture

您的留言將使用 Twitter 帳號。 登出 / 變更 )

Facebook照片

您的留言將使用 Facebook 帳號。 登出 / 變更 )

Google+ photo

您的留言將使用 Google+ 帳號。 登出 / 變更 )

連結到 %s

%d 位部落客按了讚: