The purpose of the course is to understand the fundamental of Database System.
How to use DBMS. (included) How DBMS works. ( A brief introduction )
Database System Concepts
Use of database grew last four decades
Very few people interacted directly with database system, custom did not know the backend database, they got printed report, etc. Some customs access system via phone interface. Direct user access via Internet.
Data isolation — multiple files and formats Integrity problems
Integrity constraints (e.g. account balance > 0) become part of program code Hard to add new constraints or change existing ones
Data redundancy and inconsistency Multiple , duplication of information in different files
Difficulty in accessing data Need to write a new program to carry out each new task
Concurrent access by multiple users Concurrent accessed needed for performance Uncontrolled concurrent accesses can lead to inconsistencies – E.g. two people reading a balance and updating it at the same time
Database System Concepts
1.2
©Silberschatz, Korth and Sudarshan, Bo Zhou
Database Applications
Database touch all aspects of our lives
Banking: all transactions Airlines: reservations, schedules Universities: registration, grades Sales: customers, products, purchases Manufacturing: production, inventory, orders, supply chain Human resources: employee records, salaries, tax deductions
DBMS is a software: Set of programs to access the data
Be able to manage databases. Provides an environment that is both convenient and efficient to use.
1.3
©Silberschatz, Korth and Sudarshan, Bo Zhou
Purpose of Database ystems
In the early days, database applications were built on top of Drawbacks of using to store data:
Large amount of information (data) Well organized: Definition and Manipulation Share among several users, avoid possible anomalous results Safety of the information stored, despite system crash or unauthorized access
Database System Concepts
1.1
©Silberschatz, Korth and Sudarshan, Bo Zhou
Database System
Database System
Database DBMS
Database : Collection of interrelated data (information about a particular enterprise)
Database System Concepts
1.4
©Silberschatz, Korth and Sudarshan, Bo Zhou
Purpose of Database Systems (Cont.)
Drawbacks of using (cont.)
Atomicity of updates Failures may leave database in an inconsistent state with partial updates carried out E.g. transfer of funds from one account to another should either complete or not happen at all
Database system Introduction
What is Database Systems? Purpose of Database Systems Data Abstraction Database Languages Database Users Database System Structure Application Architectures History of Database Systems