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E.F. Codd
Edgar Frank "Ted" Codd (19 August 1923 – 18 April 2003) was a British computer scientist who, while working for IBM, invented the relational model for database management, the theoretical basis for relational databases and relational database management systems. Biography Edgar Frank Codd was born in Fortuneswell, on the Isle of Portland in Dorset, England. After attending Poole Grammar School, he studied mathematics and chemistry at Exeter College, Oxford, before serving as a pilot in the RAF Coastal Command during the Second World War, flying Sunderlands. In 1948, he moved to New York to work for IBM as a mathematical programmer. Codd first worked for the company's Selective Sequence Electronic (SSEC) project and was later involved in the development of IBM 701 and 702. In 1953, dismayed by Senator Joseph McCarthy, Codd moved to Ottawa, Ontario, Canada. In 1957, he returned to the US working for IBM and from 1961 to 1965 pursuing his doctorate in computer science at the U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fortuneswell
Fortuneswell is a village in Underhill, Dorset, Underhill on the Isle of Portland, in Dorset, England. It lies on steeply sloping land on the northern edge of the island, known as Underhill, where Chesil Beach connects the island to the mainland. Adjoining Fortuneswell are Chiswell to the west and Castletown, Dorset, Castletown to the north. Fortuneswell occupies the steeper land above sea level, whereas Chiswell and Castletown occupy flat land close to sea level, next to Chesil Beach and Portland Harbour respectively. Fortuneswell has a main shopping street, and along with Easton, Dorset, Easton, is the main hub of the island's activities. Fortuneswell now includes the former hamlets of Maiden Well and Mallams. As with the rest of Portland's settlements, Fortuneswell has been designated as a Conservation area (United Kingdom), conservation area, to protect its special architectural and historic interest, since 1976. History Fortuneswell was established around a natural watercou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codd's Theorem
Codd's theorem states that relational algebra and the domain-independent relational calculus queries, two well-known foundational query languages for the relational model, are precisely equivalent in expressive power. That is, a database query can be formulated in one language if and only if it can be expressed in the other. The theorem is named after Edgar F. Codd, the father of the relational model for database management. The domain independent relational calculus queries are precisely those relational calculus queries that are invariant under choosing domains of values beyond those appearing in the database itself. That is, queries that may return different results for different domains are excluded. An example of such a forbidden query is the query "select all tuples other than those occurring in relation R", where R is a relation in the database. Assuming different domains, i.e., sets of atomic data items from which tuples can be constructed, this query returns different resu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Short Sunderland
The Short S.25 Sunderland is a British flying boat Maritime patrol aircraft, patrol bomber, developed and constructed by Short Brothers for the Royal Air Force (RAF). The aircraft took its service name from the town (latterly, city) and port of Sunderland in North East England. Developed in parallel with the civilian Short Empire, S.23 ''Empire'' flying boat, the flagship of Imperial Airways, the Sunderland was developed specifically to conform to the requirements of British Air Ministry List of Air Ministry specifications#1930.E2.80.931939, Specification R.2/33 for a long-range patrol/reconnaissance flying boat to serve with the Royal Air Force. Sharing several similarities with the S.23, it had a more advanced aerodynamic hull and was fitted with various offensive and defensive armaments, including machine gun Gun turret#Aircraft, turrets, bombs, Parachute mine, aerial mines, and depth charges. The Sunderland was powered by four Bristol Pegasus, Bristol Pegasus XVIII radial e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RAF Coastal Command
RAF Coastal Command was a formation within the Royal Air Force (RAF). It was founded in 1936, when the RAF was restructured into Fighter, Bomber and Coastal commands and played an important role during the Second World War. Maritime Aviation had been neglected in the inter-war period, due to disagreements between the Royal Navy (RN) and RAF over the ownership, roles and investment in maritime air power.Buckley, 2018. p.85 The Admiralty's main concern until 1937 was the return of the Fleet Air Arm to the Royal Navy while the RAF concentrated on the development of a bombing force to provide a deterrent. Coastal Command was referred to as the "Cinderella Service" by A V Alexander, the First Lord of the Admiralty in November 1940. Soon after RAF Coastal Area was elevated to Coastal Command, its headquarters moved from Lee-on-Solent to Northwood in northwest London. During the Second World War, Coastal Command's most important contribution was the protection of Allied convoys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during chemical reaction, reactions with other chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poole Grammar School
Poole Grammar School (commonly abbreviated to PGS) is an 11–18 selective boys grammar school and academy in the coastal town of Poole in Dorset, in the south of England. The school is twinned with Parkstone Grammar School. It is a member of the South West Academic Trust (SWAT). The school was a mathematics and computing school, with an additional specialism, cognition, added in 2006. Poole Grammar School is situated in the north of Poole, on the A349 (known locally as Gravel Hill), in a campus built in 1966, with various additions made since. History The Early School An early Poole Grammar School was built in 1628 by Thomas Robarts, Mayor of Poole. This school taught “Latin grammar and kindred subjects”. The establishment of the free school is commemorated in St James' Church, Poole and saw moderate success in the 18th century, before a decline against “competition from nonconformist academies and the general economic decline of the town,” and eventual closure in 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isle Of Portland
The Isle of Portland is a tied island, long by wide, in the English Channel. The southern tip, Portland Bill, lies south of the resort of Weymouth, Dorset, Weymouth, forming the southernmost point of the county of Dorset, England. A barrier beach called Chesil Beach joins Portland with mainland England. The A354 road passes down the Portland end of the beach and then over the Fleet Lagoon by bridge to the mainland. The population of Portland is 13,417. Portland is a central part of the Jurassic Coast, a World Heritage Site on the Dorset and east Devon coast, important for its geology and landforms. Portland stone, a limestone famous for its use in British and world architecture, including St Paul's Cathedral and the United Nations Headquarters, continues to be quarried here. Portland Harbour, in between Portland and Weymouth, is one of the largest man-made harbours in the world. The harbour was made by the building of stone breakwater (structure), breakwaters between 1848 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relational Database Management System
A relational database (RDB) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. A Relational Database Management System (RDBMS) is a type of database management system that stores data in a structured format using rows and columns. Many relational database systems are equipped with the option of using SQL (Structured Query Language) for querying and updating the database. History The concept of relational database was defined by E. F. Codd at IBM in 1970. Codd introduced the term ''relational'' 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 ''relation''. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database
In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS additionally encompasses the core facilities provided to administer the database. The sum total of the database, the DBMS and the associated applications can be referred to as a database system. Often the term "database" is also used loosely to refer to any of the DBMS, the database system or an application associated with the database. Before digital storage and retrieval of data have become widespread, index cards were used for data storage in a wide range of applications and environments: in the home to record and store recipes, shopping lists, contact information and other organizational data; in business to record presentation notes, project research and notes, and contact information; in schools as flash c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 are 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 tab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Scientist
A computer scientist is a scientist who specializes in the academic study of computer science. Computer scientists typically work on the theoretical side of computation. Although computer scientists can also focus their work and research on specific areas (such as algorithm and data structure development and design, software engineering, information theory, database theory, theoretical computer science, numerical analysis, programming language theory, compiler, computer graphics, computer vision, robotics, computer architecture, operating system), their foundation is the theoretical study of computing from which these other fields derive. A primary goal of computer scientists is to develop or validate models, often mathematical, to describe the properties of computational systems (Processor (computing), processors, programs, computers interacting with people, computers interacting with other computers, etc.) with an overall objective of discovering designs that yield useful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
