Database Systems

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Database Systems by Mind Map: Database Systems

1. The differences between:-

1.1. Data

1.1.1. Raw facts

1.1.2. Formatted for storage, processing and presentation

1.1.3. Building blocks of information

1.2. Information

1.2.1. Result of processing raw data to reveal meaning

1.2.2. Requires context to reveal meaning

1.2.3. Foundation of information Accurate, relevant, timely information is the key to good decision making Good decision making is the key to organizational survival

1.2.4. Bedrock of knowledge

1.2.5. Produced by processing data

1.2.6. Reveal meaning in data

2. Database

2.1. Shared, integrated computer structure that stores a collection of data

2.1.1. Metadata Data about data Provides description of data characteristics and relationships in data Complements and expands value of data

2.2. Can be classified according to:

2.2.1. Number of users

2.2.2. Database locations

2.2.3. Expected type and extent of use

2.3. Types of database

2.3.1. Single-user database Supports only one user at a time Desktop database- single-user, runs on PC New node

2.3.2. Multiuser database Supports multiple users at the same time Workgroup database- supports a small number Enterprise database- supports a large number

2.3.3. Centralized database Data located at a single site New node

2.3.4. Distributed database Data distributed across several different sites

2.3.5. Operational database Supports a company's day-to-day operations Transactional or production database

2.3.6. Data warehouse Stores data used for tactical or strategic decisions New node

2.3.7. New node

2.4. Why database design is important

2.4.1. Focuses on design of database structure used for end-user data

2.4.2. Well-designed database Facilitates data management Generates accurate and valuable information

2.4.3. Poorly designed database Causes difficult-to-trace errors

3. Database management system (DBMS)

3.1. Collection of programs

3.2. Manage structure and control access to data

3.3. The intermediary between the user and the database

3.3.1. Advantages of a DBMS Improved data sharing Improved data security Improved data access Improved decision making Minimized data inconsistency

3.4. Access database through the DBMS

3.5. Enables data to be shared

3.6. Integrates many users' views of the data

4. Historical Roots: Files and File Systems

4.1. Reasons:

4.1.1. Complexity of database design easier to understand

4.1.2. Understanding file system problems helps to avoid problems with DBMS systems

4.1.3. Knowledge of file system useful for converting file system to database system

4.2. Composes of collection of file holders

4.2.1. Each tagged and kept in cabinet

4.2.2. Organized by expected use

4.3. Content of each file holder logically related

4.4. Manual system served as a data repository for small data collections

4.4.1. Cumbersome for large collections

4.5. Data processing (DP) specialist

4.5.1. Wrote software that managed the data

4.5.2. Designed the application programs

4.6. Number of files increased, file systems evolved

4.6.1. Store, retrieve and modify data

4.6.2. Owned by individual or department that commissioned its creation

4.7. Data processing (DP) manager

5. Data redundancy

5.1. File system structure makes it difficult to combine data from multiple sources

5.2. Organizational structures promotes storage of same data in different locations

5.2.1. Data redundancy Same data stored unnecessarily in different places

5.2.2. Data inconsistency Different and conflicting versions of same data occur at different places

5.2.3. Data anomalies Abnormalities when all changes in redundant data not made correctly Update anomalies Insertion anomalies Deletion anomalies

5.3. Data stored in different locations unlikely to be updates consistently

6. defines and regulates the collection, storage, management, use of data

6.1. 5 major parts of a database system

6.1.1. Hardware All the system's physical devices

6.1.2. Software Operating system software DBMS software Application programs and utility software

6.1.3. People System and database administrators Database designers Systems analyst and programmers End users

6.1.4. Data The collection of facts stored in the database New node

6.1.5. Procedures Instructions and rules that govern the design and use of the database system

7. DBMS functions

7.1. Data dictionary management

7.1.1. Stores definitions of data elements and relationships in a data dictionary

7.1.2. Changes automatically recorded in the dictionary

7.1.3. Provides data abstraction, removes structural and data dependency

7.2. Data storage management

7.2.1. Creates and manages complex structures required for data storage

7.2.2. Performance tuning: activities that make the database perform more efficiently

7.2.3. Stores the database in multiple physical data files

7.3. Data transformation and presentation

7.3.1. Transform data entered to conform to required data structures

7.3.2. Transforms physically retrieved data to conform user's logical expectations

7.4. Security management

7.4.1. Creates a security system that enforces user security and data privacy

7.4.2. Determine which users can access the database, which items can be accessed

7.5. Multiuser access control

7.5.1. Uses sophisticated algorithms to ensure concurrent access does not affect integrity

8. Disadvantages of database systems

8.1. Increased costs

8.2. Management complexity

8.3. Maintaining currency

8.4. Vendor dependence

9. New node

10. New node

10.1. Shared, integrated computer structure that stores a collection of data

10.2. Metadata

10.2.1. Data about data

10.2.2. Provides description of data characteristics and relationships in data

10.2.3. Complements and expends value of data

11. New node