Download 9. Database system: 資料庫代表一組多維的資料集合，其中的紀錄

9.
Database system: 資料庫代表一組多維的資料集合，其中的紀錄彼此之間有一些特殊的關連性，允許
使用者以不同的角度來取用。 ( ↔ Flat file )
Schema: 資料庫軟體用來維護資料庫時所需的一個整體資料庫結構的描述
Subschema: 對個別使用者需求在資料庫的部份描述
Database Management System (DBMS) <fig9.2>
Distributed Database
Data Independence
Relational database model
Relation (關連表)
<Fig9.3>
tuple(row), attribute(column)
Decomposition (lossless, nonloss)
Operations: Select(rows), Project(columns), Join <Fig9.8~9.12>
SQL(Structured Query Language): select, update, delete, select
Object-oriented database model
Maintaining database integrity
Transaction: A sequence of operations that must all happen together
Transaction log
Commit point
Roll-back
Incorrect summary problem
Lost update problem
Locking Protocols
Shared lock (讀)
Exclusive lock (寫)
Wound-wait protocol
Sequential file
Indexed file
Hash file
Clustering
Collision
Data mining
Data warehouse
Data cube
Class description, Class discrimination, Cluster analysis, Association analysis, Sequential pattern analysis
16. Security
Goals: Confidentiality, Integrity, Availability
Attacks
Confidentiality → Snooping, Traffic analysis
Integrity
→ modification, masquerading, replaying, repudiation
Availability
→ Denial of Service(DoS)
Cryptography
Symmetric-key →
substitution cipher, transposition cipher, DES(56 bits), AES(128, 192, 256 bits)
Asymmetric-key
Fingerprint
Digital signature
Entity authentication
→
claimant, verifier
Something know (ex. Password)
Something possessed (ex. Identification)
Something inherent (ex. Fingerprint)
Key-distribution center(KDC)