Applications of Databases in Our Daily Life
1.1 Applications of Databases in Our Daily Life
Commercial activities involve Database. e.g. Selling a ticket in a Cinema. Cash withdrawal in Bank.
Almost all large web site /web services consists of a Content Management System (CMS).
CMS are platform consists of Database
To build a Web site, you must decide the following
- Operating System
- Web server Software
- Programming language
- Database Engine
e.g. LAMP (Linux, Apache, MySQL, PHP0
Data Acquisition devices are computerized. Fast and Accurate
Data Acquisition with new HKID in 2017
Non-contact type Smart Card http://www.scmp.com/news/hong-kong/article/1671599/smart-hong-kong-id-cards-be-replaced-2018-2022
1.2 Applications of Databases in an Organization.
data and information
Transactions
Examples of using Database Systems in Daily life
Supermarket
Public library
1.3 Introduction of Database Model
Hierarchical models
A Tree like structure. e.g. The DNS is a tree like model
Advantages: Fast in access time.
Disadvantages: Only parent and child relationship. Difficult to modify structure.
Distributed Database
DNS is also a distributed Database
Relational Model
Data are organized in TABLES. Each Table consists of Rows (RECORDs, Tuples) and Columns (FIELDs, attributes)
https://en.wikipedia.org/wiki/Domain_Name_System
Exercise
Refer to P.13 of Text Book Example 2.
It handles the transaction: Customer Order Book
Data Redundancy (Duplicated) violates Data integrity (Data validity and Data consistency)
Redesign the it into three Table
Customer, Order, Books.
The Order Table relates the Customer and Book
Actviities 3 on P.14
1.4 Basics of a Database Management System (DBMS)
Common DBMS: (Compare different DMBS in your project.
Access: A database stored in a file. Not suitable for multiple access. Usually run it PC.
Visual Foxpro, MySQL, Oracle can run on server.
Major components and Functions of a Database Management System.
- Utility programs
- Security (DCL:Data control language handles permission) - Details are out of syllabus
- Data dictionary (Meta data: Data describe data)
- Recovery
- Report Generator
- Query Language
In chapter 8 of book 1:
Six database object : Table, Form, report, query, Macro, Module.
Advantages of DBMS
- sharing of data. (Support multiple access)
- Controlling data redundancy
- Data consistency
- Data integrity
- Security of data
- Ease of data management