Intro to Database Flashcards
What is Data?
Data is a raw facts that need to be processed in order to become an information.
Types of Data
- Numbers
- Letters
- Images
- Audio
- Videos
Data vs. Information
Data are raw facts
Information is the result of processing
raw data to reveal meaning
Information requires context to reveal
meaning
Raw data must be formatted for storage, processing, and presentation
Data are the foundation of information, which is the bedrock of knowledge
Data: building blocks of information
Information produced by processing data
Information used to reveal meaning in data
Accurate, relevant, timely information is
the key to good decision making
Good decision making is the key to organizational survival
What is the database?
A collection of related data. It is often abbreviated DB. It is a collection of information organized in such a way that a computer program can quickly select desired pieces of data.
Databases can be classified according to what?
◦ Number of users
◦ Database location(s)
◦ Expected type and extent of use
Single-user database
supports only one user at a time
Multiuser database
supports multiple users at the same time
Desktop database
single-user, runs on PC
Workgroup database
supports a small number
Enterprise database
supports a large number
Type of single-user database
Desktop database
Types of multiuser database
- Workgroup database
2. Enterprise 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
Types of operational database
Transactional or production database
Data warehouse
stores data used for tactical or strategic decisions
Types of databases
- Single-user database
- Multiuser database
- Centralized database
- Distributed database
- Operational database
- Data warehouse
What is a database design?
Database design focuses on design of database structure used for end-user data
What must the designer identify with the database?
◦ Designer must identify database’s expected use
Well-designed database
◦ Facilitates data management
◦ Generates accurate and valuable information
Poorly-designed database
◦ Causes difficult-to-trace errors
Traditional File-Based Systems
A collection of application programs that perform services for the end users such as the production of reports. Each program defines and manages its own data.
Limitations of a Traditional File-Base Systems
Limitations:
- Separation & isolation of data
- Duplication of data
- Data dependence
- Incompatibility of files
Reasons for Studying File Systems
◦ Complexity of database design easier to
understand
◦ Understanding file system problems helps to
avoid problems with DBMS systems
◦ Knowledge of file system useful for converting
file system to database system
Historical Roots: Files and Files Systems
- File systems typically composed of collection of file folders, each tagged and kept in cabinet
◦ Organized by expected use - Contents of each file folder logically related
- Manual system served as a data repository
for small data collections
◦ Cumbersome for large collections - Data processing (DP) specialist converted
computer file structure from manual system
◦ Wrote software that managed the data
◦ Designed the application programs - Initially, computer files systems resembled
manual systems - As number of files increased, file systems
evolved
◦ Each file used its own application program to
store, retrieve, modify data
◦ Each file owned by individual or department
that commissioned its creation - Data processing (DP) manager
supervised the DP department - DP department’s primary activity
remained programming
Problems with File System Data Management
- Security features difficult to program
◦ Often omitted in file system environments - Summary of file system limitations:
◦ Requires extensive programming
◦ Can not perform ad hoc queries
◦ System administration complex and difficult
◦ Difficult to make changes to existing structures
◦ Security features likely to be inadequate
Structural dependence
- access to a file dependent on its own structure
◦ All file system programs must be modified to
conform to a new file structure
Structural independence
change file structure without affecting data access
Data dependence
data access changes when data storage characteristics change
Data independence
data storage characteristics do not affect data access
Data redundancy
File system structure makes it difficult to
combine data from multiple sources
◦ Vulnerable to security breaches
Organizational structure promotes storage
of same data in different locations
◦ Islands of information
Data stored in different locations unlikely
to be updated consistently
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 not made correctly
◦ Update anomalies
◦ Insertion anomalies
◦ Deletion anomalies
