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Database Design
Database design is the organization of data according to a database model. The designer determines what data must be stored and how the data elements interrelate. With this information, they can begin to fit the data to the database model.Teorey, T.J., Lightstone, S.S., et al., (2009). Database Design: Know it all.1st ed. Burlington, MA.: Morgan Kaufmann Publishers Database management system manages the data accordingly. Database design involves classifying data and identifying interrelationships. This theoretical representation of the data is called an ''ontology''. The ontology is the theory behind the database's design. Determining data to be stored In a majority of cases, a person who is doing the design of a database is a person with expertise in the area of database design, rather than expertise in the domain from which the data to be stored is drawn e.g. financial information, biological information etc. Therefore, the data to be stored in the database must be determined in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Database Model
A database model is a type of data model that determines the logical structure of a database. It fundamentally determines in which manner data can be stored, organized and manipulated. The most popular example of a database model is the relational model, which uses a table-based format. Types Common logical data models for databases include: * Hierarchical database model :It is the oldest form of data base model. It was developed by IBM for IMS (information Management System). It is a set of organized data in tree structure. DB record is a tree consisting of many groups called segments. It uses one to many relationships. The data access is also predictable. * Network model * Relational model * Entity–relationship model ** Enhanced entity–relationship model * Object model * Document model * Entity–attribute–value model * Star schema An object–relational database combines the two related structures. Physical data models include: * Inverted index * Flat file ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Computer Performance
In computing, computer performance is the amount of useful work accomplished by a computer system. Outside of specific contexts, computer performance is estimated in terms of accuracy, efficiency and speed of executing computer program instructions. When it comes to high computer performance, one or more of the following factors might be involved: * Short response time for a given piece of work. * High throughput (rate of processing work). * Low utilization of computing resource(s). ** Fast (or highly compact) data compression and decompression. * High availability of the computing system or application. * High bandwidth. * Short data transmission time. Technical and non-technical definitions The performance of any computer system can be evaluated in measurable, technical terms, using one or more of the metrics listed above. This way the performance can be * Compared relative to other systems or the same system before/after changes * In absolute terms, e.g. for fulfilling a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Concept Mapping
A concept map or conceptual diagram is a diagram that depicts suggested relationships between concepts. Concept maps may be used by instructional designers, engineers, technical writers, and others to organize and structure knowledge. A concept map typically represents ideas and information as boxes or circles, which it connects with labeled arrows, often in a downward-branching hierarchical structure but also in free-form maps. The relationship between concepts can be articulated in '' linking phrases'' such as "causes", "requires", "such as" or "contributes to". The technique for visualizing these relationships among different concepts is called ''concept mapping''. Concept maps have been used to define the ontology of computer systems, for example with the object-role modeling or Unified Modeling Language formalism. Differences from other visualizations * '' Topic maps'': Both concept maps and topic maps are kinds of knowledge graph, but topic maps were developed by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Principle Of Orthogonal Design
{{primary sources, date=March 2014 The principle of orthogonal design (abbreviated POOD) was developed by database researchers David McGoveran and Christopher J. Date in the early 1990s, and first published "A New Database Design Principle" in the July 1994 issue of Database Programming and Design and reprinted several times. It is the second of the two principles of database design, which seek to prevent databases from being too complicated or redundant, the first principle being the principle of full normalization ( POFN). Simply put, it says that no two relations in a relational database should be defined in such a way that they can represent the same facts. As with database normalization, POOD serves to eliminate uncontrolled storage redundancy and expressive ambiguity, especially useful for applying updates to virtual relations (e.g., view (database) In a database, a view is the result set of a ''stored'' query on the data, which the database users can query just as they wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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POOD
''Pood'' ( rus, пуд, r=pud, p=put, plural: or ) is a unit of mass equal to 40 ''funt'' (, Russian pound). Since 1899 it is set to approximately 16.38 kilograms (36.11 pounds). It was used in Russia, Belarus, and Ukraine. ''Pood'' was first mentioned in a number of 12th-century documents. Unlike '' funt'', which came at least in the 14th century from gmh, phunt, orv, пудъ (formerly written * ) is a much older borrowing from Late Latin "pondo", from Classical "pondus". Use in the past and present Together with other units of weight of the Imperial Russian weight measurement system, the USSR officially abolished the ''pood'' in 1924. But the term remained in widespread use at least until the 1940s. In his 1953 short story " Matryona's Place", Aleksandr Solzhenitsyn presents the ''pood'' as still in use amongst the Khrushchev-era Soviet peasants. Its usage is preserved in modern Russian in certain specific cases, e.g., in reference to sports weights, such as tradition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Relational Model
The relational model (RM) is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, where all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database. The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries. Most relational databases use the SQL data definition and query language; these systems implement what can be regarded as an engineering approximation to the relational model. A ''table'' in a SQL database schema corresponds to a predicate variable; the contents of a table to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Relational Database
A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relational database systems are equipped with the option of using the SQL (Structured Query Language) for querying and maintaining the database. History The term "relational database" was first defined by E. F. Codd at IBM in 1970. Codd introduced the term in his research paper "A Relational Model of Data for Large Shared Data Banks". In this paper and later papers, he defined what he meant by "relational". One well-known definition of what constitutes a relational database system is composed of Codd's 12 rules. However, no commercial implementations of the relational model conform to all of Codd's rules, so the term has gradually come to describe a broader class of database systems, which at a minimum: # Present the data to the user as rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Online Analytical Processing
Online analytical processing, or OLAP (), is an approach to answer multi-dimensional analytical (MDA) queries swiftly in computing. OLAP is part of the broader category of business intelligence, which also encompasses relational databases, report writing and data mining. Typical applications of OLAP include business reporting for sales, marketing, management reporting, business process management (BPM), budgeting and forecasting, financial reporting and similar areas, with new applications emerging, such as agriculture. The term ''OLAP'' was created as a slight modification of the traditional database term online transaction processing (OLTP). OLAP tools enable users to analyze multidimensional data interactively from multiple perspectives. OLAP consists of three basic analytical operations: consolidation (roll-up), drill-down, and slicing and dicing.O'Brien, J. A., & Marakas, G. M. (2009). Management information systems (9th ed.). Boston, MA: McGraw-Hill/Irwin. Consoli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Data Dictionary
A data dictionary, or metadata repository, as defined in the ''IBM Dictionary of Computing'', is a "centralized repository of information about data such as meaning, relationships to other data, origin, usage, and format". ''Oracle'' defines it as a collection of tables with metadata. The term can have one of several closely related meanings pertaining to databases and database management systems (DBMS): * A document describing a database or collection of databases * An integral component of a DBMS that is required to determine its structure * A piece of middleware that extends or supplants the native data dictionary of a DBMS Documentation The terms ''data dictionary'' and ''data repository'' indicate a more general software utility than a catalogue. A ''catalogue'' is closely coupled with the DBMS software. It provides the information stored in it to the user and the DBA, but it is mainly accessed by the various software modules of the DBMS itself, such as DDL and DML com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Index (database)
A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time a database table is accessed. Indexes can be created using one or more columns of a database table, providing the basis for both rapid random lookups and efficient access of ordered records. An index is a copy of selected columns of data, from a table, that is designed to enable very efficient search. An index normally includes a "key" or direct link to the original row of data from which it was copied, to allow the complete row to be retrieved efficiently. Some databases extend the power of indexing by letting developers create indexes on column values that have been transformed by functions or expressions. For example, an index could be created on upper(last_name), which wou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Data Type
In computer science and computer programming, a data type (or simply type) is a set of possible values and a set of allowed operations on it. A data type tells the compiler or interpreter how the programmer intends to use the data. Most programming languages support basic data types of integer numbers (of varying sizes), floating-point numbers (which approximate real numbers), characters and Booleans. A data type constrains the possible values that an expression, such as a variable or a function, might take. This data type defines the operations that can be done on the data, the meaning of the data, and the way values of that type can be stored. Concept A data type is a collection or grouping of data values. Such a grouping may be defined for many reasons: similarity, convenience, or to focus the attention. It is frequently a matter of good organization that aids the understanding of complex definitions. Almost all programming languages explicitly include the notion of da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Data Element
In metadata, the term data element is an atomic unit of data that has precise meaning or precise semantics. A data element has: # An identification such as a data element name # A clear data element definition # One or more representation terms # Optional enumerated values Code (metadata) # A list of synonyms to data elements in other metadata registries Synonym ring Data elements usage can be discovered by inspection of software applications or application data files through a process of manual or automated Application Discovery and Understanding. Once data elements are discovered they can be registered in a metadata registry. In telecommunication, the term data element has the following components: #A named unit of data that, in some contexts, is considered indivisible and in other contexts may consist of data items. #A named identifier of each of the entities and their attributes that are represented in a database. #A basic unit of information built on standard structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |