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Database

Database. Dr. Roueida Mohammed. Database Is a collection of data, typically describing the activities of one or more related organizations. For example, a university database might contain information about the following: Entities such as students, faculty, courses, and classrooms.

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Database

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  1. Database Dr. Roueida Mohammed

  2. Database • Is a collection of data, typically describing the activities of one or more related organizations. For example, a university database might contain information about the following: • Entities such as students, faculty, courses, and classrooms. • Relationships between entities, such as students' enrollment in courses, faculty teaching courses, and the use of rooms for courses.

  3. Database management system (DBMS) • DBMS is a collection of programs that enables users to create and maintain a database. • Defining a database involves specifying the data types, structures, and constraints of the data to be stored in the database. • Manipulating a database includes functions such as querying the database to retrieve specific data, updating the database to reflect changes in the miniworld, and generating reports from the data. • Sharing a database allows multiple users and programs to access the database simultaneously.

  4. Database-System Applications • Enterprise Information • Banking and Finance • Universities • Airlines • Telecommunication:

  5. The Users of a Database System • DBA once a database is created, it is the job of the database administrator to make decisions about the nature of data to be stored in the database, the access policies to be enforced (who is going to access certain parts of the database), monitoring and tuning the performance of the database, etc. • Users at the other extremity of the user range, we have the end users. These users have limited access rights, and they need to have only minimal technical knowledge of the database.

  6. ADVANTAGES OF A DBMS • Database Development: • Data independence: • Efficient data access • Data integrity and security: • Crash recovery: • Data administration and Concurrent access:

  7. Instances and Schemas • The collection of information stored in the database at a particular moment is called an instanceof the database. • The overall design of the database is called the database schema. • Database systems have several schemas, partitioned according to the levels of abstraction: • Physical schemadescribes the database design at the physical level. • Logical schemadescribes the database design at the logical level. • A database may also have several schemas at the view level, sometimes called subschemas, which describe different views of the database.

  8. Introduction to information models and data models • Information model: is an abstract, formal representation of entities that includes their properties, relationships and the operations that can be performed on them. The entities being modeled may be from the real world, such as devices on a network, or they may themselves be abstract, such as the entities used in a billing system. • Data model: a collection of conceptual tools for describing data, data relationships, data semantics, and consistency

  9. Types of data models • Relational data model. • Entity-Relationship data model. • Object based data model. • Hierarchical data model. • Network data model.

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