Database management system
- 1. Database management system Presented By : Rishi Ram Khanal BIM 4th Semester (TU) 1
- 2. Content • Introduction to DBMS • Purpose of DBMS • Data abstraction • Database model 2
- 3. Introduction • DBMS stand for database management system. • Database is a collection of data and management system. • It is a set of programs to store and retrieve data . • This system is basically developed for large .amount of data . • There are two things required optimization store of data and retrieval of data. 3
- 4. Purpose • It is a software tool that makes it possible to organize data in data base . • To store and transform data into information to support making decision . there are three type of main purpose of DBMS The physical database: the collection of files that contains the data . The database engine : the software that makes it possible to access and modify the contents of the database . 4
- 5. The database scheme: the specification of the logical structure of the data stored in the database. 5
- 6. Data abstraction • It hides complexity of data . • It hides unnecessary data and function . There are three level of data abstraction • Physical level :The lowest level abstraction describe how the data are actually stored • The physical level describe complex low- level data structures in detail . 6
- 7. Logical level : this level of abstraction describe what data are stored in the data base . • what relationship exist among those data . View level • It is the highest level of data abstraction • view level describe only part of the entire database 7
- 8. • view level describes the user interaction with database system. 8
- 9. Data base model Hierarchical Model • They build upon individual data sets and are able to express hierarchical or network like structures of the real world • The data is stored as records which are connected to one another through links. • A record is a collection of fields, with each field containing only one value 9
- 10. • The hierarchical database model mandates that each child record has only one parent, whereas each parent record can have one or more child record 10
- 11. Network level • The network model expands upon the hierarchical structure, allowing many-to- many relationships in a tree-like structure that allows multiple parents. • The network model organizes data using two fundamental concepts, called records and sets 11
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- 13. Relational model The data is stored in two-dimensional tables (rows and columns). The data is manipulated based on the relational theory of mathematics. 13
- 14. • The object model • the data is stored in the form of objects, which are structures called classes that display the data within. The fields are instances of these classes 14
- 15. ER model • The ER model defines the conceptual view of a database. • It works around real-world entities and the associations among them. 15
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