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Chapter1 Database: A collection of data stored in a standardized format, designed to be shared by multiple users. Database Management System: Software that defines a database, stores the data, supports a query language, produces reports, and creates data entry screens. Application Development: Feasibility Analysis Design Development Implementation Steps in database design : Identify business rules. Define tables and relationships. Create input forms and reports. Combine as applications for users. Components of a DBMS: Database engine the heart of the DBMS. It responsible for storing, retrieving, and updating the data. Data dictionary holds the definitions of all of the data tables. Query Processor it enables developers and users to store and retrieve data. Report writer enables you to set up the report on the screen to specify how items will be displayed or calculated. Forms generator (input screens) Helps the developer create input forms (enter data). Application generator a collection of forms and reports designed for a specific user task. - agood DBMS contains an application generator. Communications Security & other Utilities Advantages of Database Approach: Minimal data redundancy. Data consistency. Integration of data. Sharing of data. Enforcement of standards. Ease of application development. Uniform security, privacy and integrity. Data independence. Database Management Approach Data is most important Data defined first Standard format Access through DBMS Queries, Reports, Forms Application Programs 3GL Interface Data independence Change data definition without changing code Alter code without changing data Move/split data without changing code Drawback problems: Uncontrolled Duplication Inconsistent data Inflexibility Limited data sharing Poor enforcement of standards Poor programmer productivity Excessive program maintenance File Method Problems Files defined in program Multi-user problems Database Types: Hierarchical Database: To retrieve data, you must start at the top & retrieve all nested data Network Database Relational Database Object-Oriented DBMS How do you sell a DBMS approach? Applications change a lot, but same data. Need for ad hoc questions and queries. Need to reduce development times. Need shared data. Improve quality of data. Enable users to do more development. application generator A DBMS tool that assists the developer in creating a complete application package. Common tools include menu and toolbar generators and an integrated context-sensitive Help system. database A collection of data stored in a standardized format, designed to be shared by multiple users. A collection of tables for a particular business situation. database engine The heart of the DBMS. It is responsible for storing, retrieving, and updating the data. database management Software that defines a database, stores the data, supports a query language, produces reports, system (DBMS) and creates data entry screens. data dictionary Holds the definitions of all of the data tables and describes the type of data that is being stored. data independence Separates the data from the programs, which often enables the data definition to be changed without altering the program. feasibility study A quick examination of the problems, goals, and expected costs of a proposed system. The objective is to determine whether the problem can reasonably be solved with a computer system. forms generator A DBMS tool that enables you to set up input forms on the screen. hierarchical database An older DBMS type that organizes data in hierarchies that can be rapidly searched from top to bottom, e.g., Customer—Order—OrderItem. network database object-oriented (OO) database An older DBMS type that expanded the hierarchical database by supporting multiple connections between entities. A network database is characterized by the requirement that all connections had to be supported by an index. A database system that holds objects, including properties and methods. It supports links between objects, including inheritance. The use of a database for data analysis. The focus is on retrieval of the data. The primary online analytical processing (OLAP) goals are to provide acceptable response times, maintain security, and make it easy for users to find the data they need. persistent objects In object-oriented programming, the ability to store objects (in a file or database) so that they can be retrieved at a later data. persistent stored In SQL-99 a proposed method for storing methods associated with objects. The module code modules would be stored and retrieved automatically by the DBMS. relational database The most popular type of DBMS. All data is stored in tables (sometimes called relations). Tables are logically connected by the data they hold (e.g., through the key values). Relational databases should be designed through data normalization. report writer A DBMS tool that enables you to set up reports on the screen to specify how items will be displayed or calculated. Most of these tasks are performed by dragging data onto the screen. subtable I inherits all of the columns from a base table. It provides inheritance similar to that of the abstract data types; however, all data is stored in separate columns.