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Table Row
In the context of a relational database, a row—also called a tuple—represents a single, implicitly structured data item in a table. In simple terms, a database table can be thought of as consisting of ''rows'' and columns. Cory Janssen, Techopedia, retrieved 27 June 2014 Each row in a table represents a set of related data, and every row in the table has the same structure. For example, in a table that represents companies, each row would represent a single company. Columns might represent things like company name, company street address, whether the company is publicly held, its VAT number, etc. In a table that represents ''the association'' of employees with depa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 relati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuple
In mathematics, a tuple is a finite ordered list (sequence) of elements. An -tuple is a sequence (or ordered list) of elements, where is a non-negative integer. There is only one 0-tuple, referred to as ''the empty tuple''. An -tuple is defined inductively using the construction of an ordered pair. Mathematicians usually write tuples by listing the elements within parentheses "" and separated by a comma and a space; for example, denotes a 5-tuple. Sometimes other symbols are used to surround the elements, such as square brackets "nbsp; or angle brackets "⟨ ⟩". Braces "" are used to specify arrays in some programming languages but not in mathematical expressions, as they are the standard notation for sets. The term ''tuple'' can often occur when discussing other mathematical objects, such as vectors. In computer science, tuples come in many forms. Most typed functional programming languages implement tuples directly as product types, tightly associated with algebr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data
In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted. A datum is an individual value in a collection of data. Data is usually organized into structures such as tables that provide additional context and meaning, and which may themselves be used as data in larger structures. Data may be used as variables in a computational process. Data may represent abstract ideas or concrete measurements. Data is commonly used in scientific research, economics, and in virtually every other form of human organizational activity. Examples of data sets include price indices (such as consumer price index), unemployment rates, literacy rates, and census data. In this context, data represents the raw facts and figures which can be used in such a manner in order to capture the useful information out of it. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Table (database)
A table is a collection of related data held in a table format within a database. It consists of columns and rows. In relational databases, and flat file databases, a ''table'' is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows, the cell being the unit where a row and column intersect. A table has a specified number of columns, but can have any number of rows. Each row is identified by one or more values appearing in a particular column subset. A specific choice of columns which uniquely identify rows is called the primary key. "Table" is another term for "relation"; although there is the difference in that a table is usually a multiset (bag) of rows where a relation is a set and does not allow duplicates. Besides the actual data rows, tables generally have associated with them some metadata, such as constraints on the table or on the values within particular columns. The data in a table does not have to be physic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Column (database)
In a relational database, a column is a set of data values of a particular type, one value for each row of the database.The term "column" also has equivalent applications in other, more generic contexts. See e.g., Flat file database, Table (information). A column may contain text values, numbers, or even pointers to files in the operating system. Columns typically contain simple types, though some relational database systems allow columns to contain more complex data types, such as whole documents, images, or even video clips. A column can also be called an attribute. Each row would provide a data value for each column and would then be understood as a single structured data value. For example, a database that represents company contact information might have the following columns: ID, Company Name, Address Line 1, Address Line 2, City, and Postal Code. More formally, a row is a tuple containing a specific value for each column, for example: (1234, 'Big Company Inc.', '123 East ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Value Added Tax Identification Number
A value-added tax identification number or VAT identification number (VATIN) is an identifier used in many countries, including the countries of the European Union, for value-added tax purposes. In the EU, a VAT identification number can be verified online at the EU's official VIES website. It confirms that the number is currently allocated and can provide the name or other identifying details of the entity to whom the identifier has been allocated. However, many national governments will not give out VAT identification numbers due to data protection laws. The full identifier starts with an ISO 3166-1 alpha-2 (2 letters) country code (except for Greece, which uses the ISO 639-1 language code ''EL'' for the Greek language, instead of its ISO 3166-1 alpha-2 country code ''GR'', and Northern Ireland, which uses the code ''XI'' when trading with the EU) and then has between 2 and 13 characters. The identifiers are composed of numeric digits in most countries, but in some countries th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relvar
In relational databases, relvar is a term introduced by C. J. Date and Hugh Darwen as an abbreviation for Relation (database), relation variable in their 1995 paper ''The Third Manifesto'', to avoid the confusion sometimes arising from the use of the term relation, by the inventor of the relational model, E. F. Codd, for a variable to which a relation is assigned as well as for the relation itself. The term is used in Date's well-known database textbook ''An Introduction to Database Systems'' and in various other books authored or coauthored by him. Some database textbooks use the term relation (database), relation for both the variable and the data it contains. Similarly, texts on SQL tend to use the term ''table'' for both purposes, though the qualified term ''base table'' is used in the standard for the variable. A closely related term often used in academic texts is relation schema, this being a set of attributes paired with a set of constraints, together defining a set of r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Datatype
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 data ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Identifier
An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of objects, where the "object" or class may be an idea, physical countable object (or class thereof), or physical noncountable substance (or class thereof). The abbreviation ID often refers to identity, identification (the process of identifying), or an identifier (that is, an instance of identification). An identifier may be a word, number, letter, symbol, or any combination of those. The words, numbers, letters, or symbols may follow an encoding system (wherein letters, digits, words, or symbols ''stand for'' epresentideas or longer names) or they may simply be arbitrary. When an identifier follows an encoding system, it is often referred to as a code or ID code. For instance the ISO/IEC 11179 metadata registry standard defines a code as ''system of valid symbols that substitute for longer values'' in contrast to identifiers without symbolic meaning. Ide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dollar
Dollar is the name of more than 20 currencies. They include the Australian dollar, Brunei dollar, Canadian dollar, Hong Kong dollar, Jamaican dollar, Liberian dollar, Namibian dollar, New Taiwan dollar, New Zealand dollar, Singapore dollar, United States dollar, Trinidad and Tobago Dollar and several others. The symbol for most of those currencies is the dollar sign $ in the same way as many countries using peso currencies. Economies that use a "dollar" Other territories that use a "dollar" * : Eastern Caribbean dollar * (Netherlands): US dollar * : US dollar (alongside the pound sterling) * : US dollar * : Eastern Caribbean dollar * (Netherlands): US dollar * (France): Canadian dollar (alongside the euro) * (Netherlands): US dollar * : US dollar Countries unofficially accepting "dollars" * Afghanistan: US dollar * Argentina: US dollar * Bolivia: US dollar * Cambodia: US dollar * Cuba: US dollar * Guatemala: US dollar * Lebanon: US dollar * Macau: Hong Kong d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Column (database)
In a relational database, a column is a set of data values of a particular type, one value for each row of the database.The term "column" also has equivalent applications in other, more generic contexts. See e.g., Flat file database, Table (information). A column may contain text values, numbers, or even pointers to files in the operating system. Columns typically contain simple types, though some relational database systems allow columns to contain more complex data types, such as whole documents, images, or even video clips. A column can also be called an attribute. Each row would provide a data value for each column and would then be understood as a single structured data value. For example, a database that represents company contact information might have the following columns: ID, Company Name, Address Line 1, Address Line 2, City, and Postal Code. More formally, a row is a tuple containing a specific value for each column, for example: (1234, 'Big Company Inc.', '123 East ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
