Page 60 - Demo

%u062c%u0645%u064a%u0639 %u0627%u0644%u062d%u0642%u0648%u0642 %u0645%u062d%u0641%u0648%u0638%u0629 %u0640 %u0627%u0625%u0644%u0639%u062a%u062f%u0627%u0621 %u0639%u0649%u0644 %u062d%u0642 %u0627%u0645%u0644%u0624%u0644%u0641 %u0628%u0627%u0644%u0646%u0633%u062e %u0623%u0648 %u0627%u0644%u0637%u0628%u0627%u0639%u0629 %u064a%u0639%u0631%u0636 %u0641%u0627%u0639%u0644%u0647 %u0644%u0644%u0645%u0633%u0627%u0626%u0644%u0629 %u0627%u0644%u0642%u0627%u0646%u0648%u0646%u064a%u062960Chapter FourDatabases are considered one of the most important reasons for the development and progress of information systems, as the world's data are received in databases, and databases feed other reports and systems to serve the goals of the organization. Thus, databases and their applications have become an essential element in the conduct of daily life in contemporary society, as all activities practiced by members of society, such as registering births, deaths, educational results, travel documents, banking operations, and others, must deal with databases. All of the above examples today fall within the scope of traditional database applications. The goals for which the databases are located differ, and the applications that build their boxes also differ. Today, there are advanced database applications such as data mining and electronic commerce. Concepts about databases Data: They are abstract facts that are required to be entered or queried, where each statement represents an independent element such as (patient's name, room number, address, .... etc.) Information: The data that has been processed and placed in an appropriate and understandable form for the user. Entity: It is a general category that represents a thing, person, or place about which we want to save data in order to obtain information about it at a later time. Represented by a table in relational databases. Example: supplier or product. Attributes: These are the characteristics of each entity. Example: Supplier name and address or product price and description. Databases: A set of logical data elements that are linked to each other by a certain relationship. A single database can be designed to be used with many programs and applications. Database design includes defining data types, relationships, and constraints on all data. Building a database is the process of storing the data itself in a storage medium controlled by database systems. When designing a database, users and applications must be specified for which the database will be used. Databases are dealt with by using database management systems (Database Management Systems - DBMS