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21 Cards in this Set
- Front
- Back
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What is Database Management System? |
A collection of interrelated and persistent data (usually referred to as the database (DB) |
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What is Database Management System? |
A set of application programs used to access, update and manage that data (which form the data management system (MS) |
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First general purpose database by Charles Bachman from GE. Used the network data model |
Early 1960s |
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IBM developed Information Management System (IMS). Used the hierarchical data model. Led to SABRE, the airline reservation system developed by AA and IBM. Still in use today. |
Late 1960s |
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Edgar Code of IBM developed the relational data model. Led to several DBMS based on relational model, as well as important theoretical results. Code wins Turing award. |
1970 |
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Relational model dominant. SQL standard. |
1980 |
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DBMS vendors extend systems, allowing more complex data types (images, text). |
Late 1980s, 1990s |
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Why Use a DBMS? |
1. Data independence and efficient access.2. Reduced application development time.3. Data integrity and security.4. Uniform data administration.5. Concurrent access, recovery from crashes. |
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Purpose of DBMS |
1. Data redundancy and inconsistency 2. Difficulty in new program to carry out each new task 3. Data isolation 4. Security problems 5. Integrity problems |
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Organizes data in a tree structure. There is a hierarchy of parent and child data segments. |
Data models; Hierarchical Model |
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Permitted the modeling of many-to- many relationships in data |
Network Model |
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Allows the definition of data structures, storage and retrieval operations and integrity constraints. |
Relational Model |
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Add database functionality to object programming languages. They bring much more than persistent storage of programming language objects. |
Object-Oriented Model |
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The information that is normally associated with a schema is contained within the data, which is sometimes called``selfdescribing''. |
Semi structured Model |
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Three levels or layers of DBMS architecture: |
1. External Level 2. Conceptual Level 3. Internal Level |
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Is described by a schema i.e. it consists of definition of logical records and relationship in the external view. |
External Level |
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Represents the entire database. Conceptual schema describes the records and relationship included in the Conceptual view. |
Conceptual Level |
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Indicates hoe the data will be stored and described the data structures and access method to be used by the database. |
Internal level |
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Components of DBMS |
1. Hardware 2. Software 3. Data 4. People 5. Procedure |
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Advantage of DBMS |
1. Controlling Redundancy 2. Sharing of Data 3. Data Consistency 4. Integration of Data 5. Integration Constraints 6. Data Security 7. Report Writers 8. Control Over Concurrency 9. Backup and Recovery Procedures 10. Data Independence |
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Disadvantage of DBMS |
1..Cost of Hardware and Software 2. Cost of Data Conversion 3. Cost of Staff Training 4. Appointing Technical Staff 5. Database Damage |
