Презентация Lecture1. 2Data Model онлайн

Содержание слайда: Data Model Data Model hierarchical network relational post-relational multidimensional object-oriented

Содержание слайда: The data model is a description of the organization of data in the database. The data model is a description of the organization of data in the database. The data model also describes the relationship between the data and restrictions applicable to the data. Data models can be divided into two categories: Object - a logical model - focuses on the description of data, data relationships, and limiting. Logical model based on the entries - focuses on the description of the data structures and access methods in the database management system.

Содержание слайда: Classic models: Classic models: hierarchical Network Relational Current models: -post-relational -multidimensional -object-oriented Other data models that extend the known models object-relational deductive object-oriented, semantic, conceptual, and others.

Содержание слайда: ADVANTAGES hierarchical model Effective use of computer memory Good performance of time to perform basic operations Model is convenient to work with hierarchically structured information ADVANTAGES hierarchical model Effective use of computer memory Good performance of time to perform basic operations Model is convenient to work with hierarchically structured information DISADVANTAGES hierarchical model Cumbersome to process information with a fairly complex logical relationships Complexity of understanding for the average user Examples of database hierarchical model IMS, PC / Focus, Team-Up and Data Edge, (from Russian): Ока, ИНЭС и МИРИС

Содержание слайда: ADVANTAGES network model: The possibility of effective implementation in terms of memory consumption and speed (Compared to the hierarchical) great opportunities in terms of the admissibility of arbitrary relationships education ADVANTAGES network model: The possibility of effective implementation in terms of memory consumption and speed (Compared to the hierarchical) great opportunities in terms of the admissibility of arbitrary relationships education DISADVANTAGES network model High complexity and rigidity of the database schema The difficulty for the understanding and implementation of information processing in the database as a regular user Known network database: IDMS, db_VistaIII, СЕТЬ, СЕТОР и КОМПАС

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Содержание слайда: ADVANTAGES relational model Simplicity, ease the physical implementation on a computer Processing efficiency ADVANTAGES relational model Simplicity, ease the physical implementation on a computer Processing efficiency DISADVANTAGES relational model Lack of standard means of identification of individual records Complexity of the description of hierarchical and network links Examples of relational database model: dBaseIIIPlus и dBaseIY ( фирма Ashton-Tate), DB2(IBM), R: BASE (Microrim), FoxPro ранних версий и FoxBase (Fox Software), Paradox и dBASE for Windows (Borland), FoxPro б.поздних версий, Visual FoxPro и Access (Microsoft), Clarion (Clarion Software), Ingres (ASK Computer Systems)и Oracle (Oracle) (from Russian): ПАЛЬМА (ИК АН УССР), HyTech (МИФИ) Object-relational: Oracle 8.x

Содержание слайда: ADVANTAGES post-relational model The possibility of representing the aggregate related relational tables with a single post-relational table, so - clear presentation of information and increase the effectiveness of its treatment ADVANTAGES post-relational model The possibility of representing the aggregate related relational tables with a single post-relational table, so - clear presentation of information and increase the effectiveness of its treatment DISADVANTAGES post-relational model The difficulty in solving the problem of ensuring the integrity and consistency of data stored Examples of post-relational database model: uniVers, Bubba и Dasdb

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Содержание слайда: ADVANTAGES multivariate model Convenience and efficiency analysis of large amounts of data related to the time (in rel.m. - nonlinear increase complexity of operations) ADVANTAGES multivariate model Convenience and efficiency analysis of large amounts of data related to the time (in rel.m. - nonlinear increase complexity of operations) DISADVANTAGES multivariate model Cumbersome for the simplest of tasks common operational processing EXAMPLES database multidimensional model Essbase (Arbor Software), Media Multi-matrix (Speedware), Oracle Express Server (Oracle) и Cache (InterSystems) Relational-dimensional model: Media/MR (Speedware) Multidimensional object-relational model: Cache

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Содержание слайда: ADVANTAGES OOM (versus relational) The ability to display information about the complex relationships of objects OOM can identify individual records database and the responsibilities of their treatment ADVANTAGES OOM (versus relational) The ability to display information about the complex relationships of objects OOM can identify individual records database and the responsibilities of their treatment DISADVANTAGES OOM High conceptual complexity The disadvantage of the data and the low speed of queries EXAMPLES database OOM POET (POET Software), Jasmine (Computer Associates), Versant (Versant Technologies), 02 (Ardent Software), ODB-Jupiter (науч.произв. центр «ИнтеллекПлюс»), Iris, Orion и Postgres.

Содержание слайда: There are a variety of object-oriented models. The most widely used model is the "entity - relationship" (ER model). There are a variety of object-oriented models. The most widely used model is the "entity - relationship" (ER model). Model "entity - relationship" is based on a realistic view which encompasses a set of objects or entities and their relationships. Schema components of ER are: entity ; connection; attributes.

Содержание слайда: The entity is any object, place, person, or action, details of which are recorded. The entity is any object, place, person, or action, details of which are recorded. Entities are represented as rectangles, on which are written the names assigned to them. There are two types of entities: dependent; independent. Affiliated entities are also referred to as weak entities, and independent - regular entities. Weak entity represented by a rectangle outlined by the double line.

Содержание слайда: Combining entities are called connection. Combining entities are called connection. Relationship is depicted in the form of diamond with the name of the link. can attach an entity to itself. Between the same entities may also be multiple connections. Connections are of three types: one-to-one; one-to-many; many-to-many.

Содержание слайда: Attribute called property of this entity. Attribute called property of this entity. Attributes are represented as ellipses, equipped name properties. Key attributes are underlined. Connection can also have attributes.

Содержание слайда: Data Model, examples of models: hierarchical network relational post-relational model multi-dimensional object-oriented