Topic 1: Overview of Database Flashcards
define data and infomation
Data are raw facts, foundation of information.
Information is the result of processed data to reveal meaning.
4 problem of File System Data Processing
- security features difficult to program
limitation:
- cannot perform ad hoc queries
- complex system administrations
- difficult to make change to existing structures
- require extensive programming
structural dependence and independence
structural dependence: access of a file is dependent on its own structure
structural independence: the file structure change without changing its data access
data dependence and independence
data dependence: data access change when data characteristics change
data independence: data access does not change when data characteristics change
what is data redundancy
same data stored unnecessarily in different places
- Data inconsistency: different and conflicting versions of same data occur at different places
- Data anomalies: abnormalities when all changes in redundant data are not made correctly
3 types of data anomalies
- Update anomalies
- Insertion anomalies
- Deletion anomalies
define database and DBMS
Database: shared, integrated computer structure that stores a collection of data.
DBMS: collection of programs that manages structure and controls access to data
3 roles of DBMS
- intermediary between user and the database
- to share data
- integrate many users view of data
5 benefits of DBMS
- improve data sharing
- improve data access
- improve data integration
- improve data security
- minimize data inconsistency
4 types of database
- Centralized database: data located at a single site
- Distributed database: data distributed across several different sites
- Operational database: supports a company’s day-to-day operations (e.g. transactional/production)
- Data warehouse: stores data used for tactical or strategic decisions
how is a well-design database
- Facilitates data management
- Generates accurate and valuable information
- Consistent
- Efficient execution
how is a poorly designed database
- difficult to trace errors
- Generate wrong information
define database system
to defines and regulates the collection, storage, management, use of data
5 major parts in database system
- people: all user of the database
- hardware: all physical devices
- software: OS, DBMS, application program
- data: all the facts
- procedure: instruction and rules
functions of database system
- data integrity management
- data dictionary management
- data storage management
- communication interface
- back up and recovery management
- multiuser access control
- security management
