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A database is an organized collection of data. The term originated within the computer industry, but its meaning has been broadened by popular use, to the extent that the European Database Directive (which creates intellectual property rights for databases) includes non-electronic databases within its definition. This article is confined to a more technical use of the term; though even amongst computing professionals, some attach a much wider meaning to the word than others. The European Union (EU) directive 96/9/EC of the European Parliament and of the Council of 11 March 1996 on the legal protection of databases is an intellectual property directive requiring EU member states to protect databases both by copyright and by a sui generis right that controls extraction...
One possible definition is that a database is a collection of records stored in a computer in a systematic way, such that a computer program can consult it to answer questions. For better retrieval and sorting, each record is usually organized as a set of data elements (facts). The items retrieved in answer to queries become information that can be used to make decisions. The computer program used to manage and query a database is known as a database management system (DBMS). The properties and design of database systems are included in the study of information science. In computer science, a database record is a description of a single item as stored in a database. ...
// A computer program or software program (usually abbreviated to a program) is a step-by-step list of instructions written for a particular computer architecture in a particular computer programming language. ...
In metadata, the term data element is an atomic unit of data that has: an identification such as a Data element name a clear Data element definition one or more Representation terms optional enumerated values In telecommunication, the term data element has the following components: A named unit of data...
Information is a word which has many different meanings in everyday usage and in specialized contexts, but as a rule, the concept is closely related to others such as data, instruction, knowledge, meaning, communication, representation, and mental stimulus. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
Information science or informatics is the science of information. ...
The central concept of a database is that of a collection of records, or pieces of knowledge. Typically, for a given database, there is a structural description of the type of facts held in that database: this description is known as a schema. The schema describes the objects that are represented in the database, and the relationships among them. There are a number of different ways of organizing a schema, that is, of modelling the database structure: these are known as database models (or data models). The model in most common use today is the relational model, which in layman's terms represents all information in the form of multiple related tables each consisting of rows and columns (the true definition uses mathematical terminology). This model represents relationships by the use of values common to more than one table. Other models such as the hierarchical model and the network model use a more explicit representation of relationships. A database model is a theory or specification describing how a database is structured and used. ...
The relational model for management of a database is a data model based on predicate logic and set theory. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
The network model is a database model conceived as a more flexible alternative to the hierarchical model. ...
Strictly speaking, the term database refers to the collection of records, and the software should be referred to as the database management system or DBMS. When the context is unambiguous, however, many database administrators and programmers use the term database to cover both meanings.
Many professionals would consider a collection of data to constitute a database only if it has certain properties: for example, if the data is managed to ensure its integrity and quality, if it allows shared access by a community of users, if it has a schema, or if it supports a query language. However, there is no agreed definition of these properties. Query languages are computer languages used to make queries into databases and information systems. ...
Database management systems are usually categorized according to the data model that they support: relational, object-relational, network, and so on. The data model will tend to determine the query languages that are available to access the database. A great deal of the internal engineering of a DBMS, however, is independent of the data model, and is concerned with managing factors such as performance, concurrency, integrity, and recovery from hardware failures. In these areas there are large differences between products.
History
The earliest known use of the term data base was in June 1963, when the System Development Corporation sponsored a symposium under the title Development and Management of a Computer-centered Data Base. Database as a single word became common in Europe in the early 1970s and by the end of the decade it was being used in major American newspapers. (Databank, a comparable term, had been used in the Washington Post newspaper as early as 1966.) 1963 (MCMLXIII) was a common year starting on Tuesday (link will take you to calendar). ...
System Development Corporation, based in Los Angeles, California, was spun off from RAND Corporation in 1957. ...
Europe forms the westernmost part of Eurasia. ...
The 1970s in its most obvious sense refers to the decade between 1970 and 1979. ...
1966 was a common year starting on Saturday (link goes to calendar) // Events January January 1 - In a coup, Colonel Jean-Bédel Bokassa ousts president David Dacko and takes over the Central African Republic. ...
The first database management systems were developed in the 1960s. A pioneer in the field was Charles Bachman. Bachman's early papers show that his aim was to make more effective use of the new direct access storage devices becoming available: until then, data processing had been based on punched cards and magnetic tape, so that serial processing was the dominant activity. Two key data models arose at this time: CODASYL developed the network model based on Bachman's ideas, and (apparently independently) the hierarchical model was used in a system developed by North American Rockwell, later adopted by IBM as the cornerstone of their IMS product. The 1960s in its most obvious sense refers to the decade between 1960 and 1969, but the expression has taken on a wider meaning over the past twenty years. ...
Charles W. Bachman is a prominent computer scientist, particularly in the area of databases. ...
The punch card (or Hollerith card) is a recording medium for holding information for use by automated data processing machines. ...
Magnetic tape is a non-volatile storage medium consisting of a magnetisable coating on a thin plastic strip. ...
A data model is a model that describes in an abstract way how data is represented in a business organization, an information system or a database management system. ...
CODASYL (often spelt Codasyl) is an acronym for COnference on DAta SYstems Languages. This was a IT industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers. ...
The network model is a database model conceived as a more flexible alternative to the hierarchical model. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
Rockwell International was the ultimate incarnation of a series of companies under the sphere of influence of Willard Rockwell, who had made his fortune after the invention and successful launch of a new bearing system for truck axles in 1919. ...
International Business Machines Corporation (IBM, or colloquially, Big Blue) NYSE: IBM (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, NY, USA. The company manufactures and sells computer hardware, software, and services. ...
Information Management System (IMS) is a joint hierarchical database and information management system. ...
The relational model was proposed by E. F. Codd in 1970. He criticized existing models for confusing the abstract description of information structure with descriptions of physical access mechanisms. For a long while, however, the relational model remained of academic interest only. While CODASYL systems and IMS were conceived as practical engineering solutions taking account of the technology as it existed at the time, the relational model took a much more theoretical perspective, arguing (correctly) that hardware and software technology would catch up in time. Among the first implementations were Michael Stonebraker's Ingres at Berkeley, and the System R project at IBM. Both of these were research prototypes, announced during 1976. The first commercial products, Oracle and DB2, did not appear until around 1980. The first successful database product for microcomputers was dBASE for the CP/M and PC-DOS/MS-DOS operating systems. The relational model for management of a database is a data model based on predicate logic and set theory. ...
Edgar F. Ted Codd (August 23, 1923 - April 18, 2003) was a British computer scientist who made seminal contributions to the theory of relational databases. ...
1970 (MCMLXX) was a common year starting on Thursday. ...
CODASYL (often spelt Codasyl) is an acronym for COnference on DAta SYstems Languages. This was a IT industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers. ...
The acronym IMS may refer to: Intramuscular Stimulation, an enhanced acupuncture technique used in physiotherapy for pain treatment Immunomagnetic separation, a laboratory test The Indianapolis Motor Speedway Information Management System, a combination database management system and transaction processing system from IBM Irritable Male Syndrome, the male equivalent of PMS IP...
Michael Stonebraker is a computer scientist specializing in database research and development. ...
This article is about a relational database system. ...
University of California, Berkeley The University of California, Berkeley (also known as Cal, UCB, UC Berkeley, The University of California, California, or simply Berkeley) is a public coeducational university situated east of the San Francisco Bay in Berkeley, California, overlooking the Golden Gate. ...
System R is a database system built as a research project at IBM San Jose Research (now IBM Almaden Research Center) in the 1970s. ...
International Business Machines Corporation (IBM, or colloquially, Big Blue) NYSE: IBM (incorporated June 15, 1911, in operation since 1888) is headquartered in Armonk, NY, USA. The company manufactures and sells computer hardware, software, and services. ...
1976 (MCMLXXVI) is a leap year starting on Thursday (link will take you to calendar). ...
An Oracle is a person or agency considered to be a source of wise counsel or prophetic opinion; an infallible authority, usually spiritual in nature. ...
DB2® is IBMs family of information management software products. ...
1980 (MCMLXXX) was a leap year starting on Tuesday. ...
dBASE III The title of this article begins with a capital letter due to technical restrictions. ...
CP/M is an operating system created for Intel 8080/85 and Zilog Z80 based microcomputers by Gary Kildall of Digital Research, Inc. ...
IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ...
Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ...
During the 1980s, research activity focused on distributed database systems and database machines, but these developments had little effect on the market. Another important theoretical idea was the Functional Data Model, but apart from some specialized applications in genetics, molecular biology, and fraud investigation, the world took little notice. The 1980s in its most obvious sense refers to the decade between 1980 and 1989. ...
A distributed database is a database that is under the control of a central database management system in which storage devices are not all attached to a common CPU. It may be stored in multiple computers located in the same physical location, or may be dispersed over a network of...
In the 1990s, attention shifted to object-oriented databases. These had some success in fields where it was necessary to handle more complex data than relational systems could comfortably cope with: spatial databases, engineering data (including software engineering repositories,) and multimedia data. Some of these ideas were adopted by the relational vendors, who integrated new features into their products as a result; the independent object database vendors largely disappeared from the scene. // Events and trends The 1990s are generally classified as having moved slightly away from the more conservative 1980s, but otherwise retaining a similar mindset. ...
An OODBMS (object-oriented database management system) is a system offering DBMS facilities in an object-oriented programming environment. ...
A repository is a central place where data is stored and maintained. ...
In the 2000s, the fashionable area for innovation is the XML database. As with object databases, this has spawned a new collection of startup companies, but at the same time the key ideas are being integrated into the established relational products. XML databases aim to remove the traditional divide between documents and data, allowing all of an organization's information resources to be held in one place, whether they are highly structured or not. Saddam Hussein shortly after his capture Major controversy over U. S. presidential election (November 7-December 13, 2000) September 11, 2001 terrorist attack on New Yorks World Trade Center and Virginias Pentagon killing almost 3000 people. ...
There are two major classes of XML database. ...
Database models Various techniques are used to model data structure. Most database systems are built around one particular data model, although it is increasingly common for products to offer support for more than one model. For any one logical model various physical implementations may be possible, and most products will offer the user some level of control in tuning the physical implementation, since the choices that are made have a significant effect on performance. An example of this is the relational model: all serious implementations of the relational model allow the creation of indexes which provide fast access to rows in a table if the values of certain columns are known.
A data model is not just a way of structuring data: it also defines a set of operations that can be performed on the data. The relational model, for example, defines operations such as selection, projection, and join. Although these operations may not be explicit in a particular query language, they provide the foundation on which a query language is built.
Flat model Some would disagree that this qualifies as a data model, as defined above.
The flat (or table) model consists of a single, two-dimensional array of data elements, where all members of a given column are assumed to be similar values, and all members of a row are assumed to be related to one another. For instance, columns for name and password might be used as a part of a system security database. Each row would have the specific password associated with an individual user. Columns of the table often have a type associated with them, defining them as character data, date or time information, integers, or floating point numbers. This model is, incidentally, a basis of the spreadsheet. A flat file database is described by a very simple database model, where all the information is stored in a plain text file, one database record per line. ...
DATA (Debt, AIDS, Trade, Africa) was established in 2002 by Bono (Paul Hewson) of the Rock band U2, and Bobby Shriver, along with activists from the Jubilee 2000 Drop the Debt Campaign, as an organisaton focused on Justice, not charity. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
Network model The network model (defined by the CODASYL specification) organizes data using two fundamental constructs, called records and sets. Records contain fields (which may be organized hierarchically, as in COBOL). Sets (not to be confused with mathematical sets) define one-to-many relationships between records: one owner, many members. A record may be an owner in any number of sets, and a member in any number of sets. A network model database management system has a more flexible structure than the hierarchical model or relational model, but pays for it in processing time and specialization of types. ...
CODASYL (often spelt Codasyl) is an acronym for COnference on DAta SYstems Languages. This was a IT industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers. ...
COBOL is a third-generation programming language. ...
The operations of the network model are navigational in style: a program maintains a current position, and navigates from one record to another by following the relationships in which the record participates. Records can also be located by supplying key values.
Although it is not an essential feature of the model, network databases generally implement the set relationships by means of pointers that directly address the location of a record on disk. This gives excellent retrieval performance, at the expense of operations such as database loading and reorganization.
Relational model The relational model was introduced in an academic paper by E. F. Codd in 1970 as a way to make database management systems more independent of any particular application. It is a mathematical model defined in terms of predicate logic and set theory. The relational model for management of a database is a data model based on predicate logic and set theory. ...
Edgar F. Ted Codd (August 23, 1923 - April 18, 2003) was a British computer scientist who made seminal contributions to the theory of relational databases. ...
1970 (MCMLXX) was a common year starting on Thursday. ...
...
Set theory is the mathematical theory of sets, which represent collections of abstract objects. ...
The products that are generally referred to as relational databases (for example, Ingres, Oracle, DB2, and SQL Server) in fact implement a model that is only an approximation to the mathematical model defined by Codd. The data structures in these products are tables, rather than relations: the main differences being that tables can contain duplicate rows, and that the rows (and columns) can be treated as being ordered. The same criticism applies to the SQL language which is the primary interface to these products. There has been considerable controversy, mainly due to Codd himself, as to whether it is correct to describe SQL implementations as "relational": but the fact is that the world does so, and the following description uses the term in its popular sense. A relational database is a database based on the relational model. ...
This article is about a relational database system. ...
An Oracle is a person or agency considered to be a source of wise counsel or prophetic opinion; an infallible authority, usually spiritual in nature. ...
DB2® is IBMs family of information management software products. ...
Mostly it refers to the Microsoft SQL Server, which was actually derived from Sybase SQL Server ...
SQL (short for Structured Query Language) is the most popular computer language used to create, modify and retrieve data from relational database management systems. ...
A relational database contains multiple tables, each similar to the one in the "flat" database model. Relationships between tables are not defined explicitly; instead, keys are used to match up rows of data in different tables. A key is a collection of one or more columns in one table whose values match corresponding columns in other tables: for example, an Employee table may contain a column named Location which contains a value that matches the key of a Location table. Any column can be a key, or multiple columns can be grouped together into a single key. It is not necessary to define all the keys in advance; a column can be used as a key even if it was not originally intended to be one.
A key that can be used to uniquely identify a row in a table is called a unique key. Typically one of the unique keys is the preferred way to refer to row; this is defined as the table's primary key.
A key that has an external, real-world meaning (such as a person's name, a book's ISBN, or a car's serial number), is sometimes called a "natural" key. If no natural key is suitable (think of the many people named Brown), an arbitrary key can be assigned (such as by giving employees ID numbers). In practice, most databases have both generated and natural keys, because generated keys can be used internally to create links between rows that cannot break, while natural keys can be used, less reliably, for searches and for integration with other databases. (For example, records in two independently developed databases could be matched up by social security number, except when the social security numbers are incorrect, missing, or have changed.) The International Standard Book Number, or ISBN (sometimes pronounced is-ben), is a unique identifier for books, intended to be used commercially. ...
This article needs cleanup. ...
Relational operations Users (or programs) request data from a relational database by sending it a query that is written in a special language, usually a dialect of SQL. Although SQL was originally intended for end-users, it is much more common for SQL queries to be embedded into software that provides an easier user interface. (Many web sites — including MediaWiki which is the engine that runs Wikipedia — perform SQL queries when generating pages.) SQL (short for Structured Query Language) is the most popular computer language used to create, modify and retrieve data from relational database management systems. ...
MediaWiki is a Wiki software package licensed under the GNU General Public License. ...
In response to a query, the database returns a result set, which is just a list of rows containing the answers. The simplest query is just to return all the rows from a table, but more often, the rows are filtered in some way to return just the answer wanted.
Often, data from multiple tables gets combined into one, by doing a join. Conceptually, this is done by taking all possible combinations of rows (the "cross-product"), and then filtering out everything except the answer. In practice, relational database management systems rewrite ("optimize") queries to perform faster, using a variety of techniques. A join combines records from two or more tables in a relational database. ...
The query optimizer is a component of database management system that is used to analyzes queries submitted to database server for execution, and then determines the optimal way to execute the query. ...
The flexibility of relational databases allows programmers to write queries that were not anticipated by the database designers. As a result, relational databases can be used by multiple applications in ways the original designers did not foresee, which is especially important for databases that might be used for decades. This has made the idea and implementation of relational databases very popular with businesses.
Dimensional model The dimensional model is a specialized adaptation of the relational model used to represent data in data warehouses in a way that data can be easily summarized using OLAP queries. In the dimensional model, a database consists of a single large table of facts that are described using dimensions and measures. A dimension provides the context of a fact (such as who participated, when and where it happened, and its type) and is used in queries to group related facts together. Dimensions tend to be discrete and are often hierarchical; for example, the location might include the building, state, and country. A measure is a quantity describing the fact, such as revenue. It's important that measures can be meaningfully aggregated - for example, the revenue from different locations can be added together. A dimensional database is one which, rather than storing data in multiple two dimensional tables (as a relational databases does), represents key data entities as different dimensions. ...
A data warehouse is, primarily, a record of an enterprises past transactional and operational information, stored in a database designed to favour efficient data analysis and reporting (especially OLAP). ...
OLAP is an acronym for online analytical processing. ...
In an OLAP query, dimensions are chosen and the facts are grouped and added together to create a summary.
The dimensional model is often implemented on top of the relational model using a star schema, consisting of one table containing the facts and surrounding tables containing the dimensions. Particularly complicated dimensions might be represented using multiple tables, resulting in a snowflake schema. The star schema (sometimes referenced as star join schema) is the simplest data warehouse schema, consisting of a single fact table with a compound primary key, with one segment for each dimension and with additional columns of additive, numeric facts. ...
The snowflake schema is a more complex data warehouse model than a star schema, and is a type of star schema. ...
A data warehouse can contain multiple star schemas that share dimension tables, allowing them to be used together. Coming up with a standard set of dimensions is an important part of dimensional modeling.
Object database models In recent years, the object-oriented paradigm has been applied to database technology, creating a new programming model known as object databases. These databases attempt to bring the database world and the application programming world closer together, in particular by ensuring that the database uses the same type system as the application program. This aims to avoid the overhead (sometimes referred to as the impedance mismatch) of converting information between its representation in the database (for example as rows in tables) and its representation in the application program (typically as objects). At the same time object databases attempt to introduce the key ideas of object programming, such as encapsulation and polymorphism, into the world of databases. Object-oriented programming (OOP) is a computer programming paradigm in which a software system is modeled as a set of objects that interact with each other. ...
An object database is a database in which information is represented in the form of objects. ...
On computer science, a datatype (often simply type) is a name or label for a set of values and some operations which can be performed on that set of values. ...
Impedance mismatch has two meanings. ...
Encapsulation may refer to: (in the vernacular) expressing an idea with few words, such as with an adage, proverb, slogan, or jingle (in software engineering) the use of information hiding within a program (in electronics) the design and manufacture of protective packages for integrated circuit encapsulation (in biomedical engineering) a...
In computer science, polymorphism is the idea of allowing the same definitions to be used with different types of data (specifically, different classes of objects), resulting in more general and abstract implementations. ...
A variety of ways have been tried for storing objects in a database. Some products have approached the problem from the application programming end, by making the objects manipulated by the program persistent. This also typically requires the addition of some kind of query language, since conventional programming languages do not have the ability to find objects based on their information content. Others have attacked the problem from the database end, by defining an object-oriented data model for the database, and defining a database programming language that allows full programming capabalities as well as traditional query facilities. Persistence is the term used in computer science to describe a capability used by a computer programmer to store data structures in non-volatile storage such as a file system or a relational database. ...
Object databases suffered because of a lack of standardization: although standards were defined by ODMG, they were never implemented well enough to ensure interoperability between products. Nevertheless, they have been used successfully in many applications: usually specialized applications such as engineering databases or molecular biology databases rather than mainstream commercial data processing. However, object database ideas were picked up by the relational vendors and influenced extensions made to these products and indeed to the SQL language. The Object Data Management Group (ODMG) was formed to deal with the issue of storing objects persistently in a standardized way. ...
SQL (short for Structured Query Language) is the most popular computer language used to create, modify and retrieve data from relational database management systems. ...
Database Internals
Indexing All of these kinds of database can take advantage of indexing to increase their speed, and this technology has advanced tremendously since its early uses in the 1960s and 1970s. The most common kind of index is a sorted list of the contents of some particular table column, with pointers to the row associated with the value. An index allows a set of table rows matching some criterion to be located quickly. Various methods of indexing are commonly used; B-trees, hashes, and linked lists are all common indexing techniques. The 1960s in its most obvious sense refers to the decade between 1960 and 1969, but the expression has taken on a wider meaning over the past twenty years. ...
The 1970s in its most obvious sense refers to the decade between 1970 and 1979. ...
B-trees are tree data structures that are most commonly found in databases and filesystem implementations. ...
Often used as a way to describe the number sign (#), particularly outside of North America. ...
In computer science, a linked list is one of the fundamental data structures used in computer programming. ...
Relational DBMSs have the advantage that indices can be created or dropped without changing existing applications, because applications don't use the indices directly. Instead, the database software decides on behalf of the application which indices to use. The database chooses between many different strategies based on which one it estimates will run the fastest.
Relational DBMSs utilize many different algorithms to compute the result of an SQL statement. The RDBMs will produce a plan of how to execute the query, which is generated by analysing the run times of the different algorithms and selecting the quickest. Some of the key algorithms that deal with joins are Nested Loops Join, Sort-Merge Join and Hash Join. SQL (short for Structured Query Language) is the most popular computer language used to create, modify and retrieve data from relational database management systems. ...
A join combines records from two or more tables in a relational database. ...
The Sort-Merge Join is an example of a join algorithm and is used in the implementation of a relational database management system. ...
The Hash Join is an example of a join algorithm and is used in the implementation of a relational database management system. ...
Transactions and concurrency In addition to their data model, most practical databases ("transactional databases") attempt to enforce a database transaction model that has desirable data integrity properties. Ideally, the database software should enforce the ACID rules, summarized here: A database transaction is a unit of interaction with a database management system or similar system that is treated in a coherent and reliable way independent of other transactions that must be either entirely completed or aborted. ...
An acid (often represented by the generic formula AH) is typically a water-soluble, sour-tasting chemical compound. ...
- Atomicity - Either all the tasks in a transaction must be done, or none of them. The transaction must be completed, or else it must be undone (rolled back).
- Consistency - Every transaction must preserve the integrity constraints -- the declared consistency rules -- of the database. It cannot place the data in a contradictory state.
- Isolation - Two simultaneous transactions cannot interfere with one another. Intermediate results within a transaction are not visible to other transactions.
- Durability - Completed transactions cannot be aborted later or their results discarded. They must persist through (for instance) restarts of the DBMS after crashes.
In practice, many DBMS's allow most of these rules to be selectively relaxed for better performance. In computer science, an atomic operation is one that either completes fully, or has no lasting effect. ...
Consistency has three technical meanings: In mathematics and logic, as well as in theoretical physics, it refers to the proposition that a formal theory or a physical theory contains no contradictions. ...
Isolation can refer to: Isolation as a psychological phenomenon (see also Solitude). ...
In computer science, durability is the ACID property that guarantees that transactions that are successfully committed will survive permanently and will not be undone by system failure. ...
Concurrency control is a method used to ensure that transactions are executed in a safe manner and follow the ACID rules. The DBMS must be able to ensure that only serializable, recoverable schedules are allowed, and that no actions of committed transactions are lost while undoing aborted transactions. In computer science -- more specifically, in the field of databases -- concurrency control is a method used to ensure that database transactions are executed in a safe manner (i. ...
Replication Replication of databases is closely related to transactions. If a database can log its individual actions, it is possible to create a duplicate of the data in realtime. The duplicate can be used to improve Performance or Availability of the whole database system. Common replication concepts include: - Master/Slave Replication: All write requests are performed on the master and then replicated to the slaves
- Quorum: The result of Read and Write requests is calculated by quering a "majority" of replicas.
- Multimaster: Two or more replicas sync each other via a transaction identifier.
Applications of databases Databases are used in many applications, spanning virtually the entire range of computer software. Databases are the preferred method of storage for large multiuser applications, where coordination between many users is needed. Even individual users find them convenient, though, and many electronic mail programs and personal organizers are based on standard database technology. Software database drivers are available for most database platforms so that application software can use a common application programming interface (API) to retrieve the information stored in a database. Two commonly used database APIs are JDBC and ODBC. A screenshot of computer software in action. ...
Application software is a loosely defined subclass of computer software that employs the capabilities of a computer directly to a task that the user wishes to perform. ...
API with 3 clients, using the Unified Modeling Language notation An application programming interface (API) is a set of definitions of the ways one piece of computer software communicates with another. ...
Java Database Connectivity, or JDBC, is an API for the Java programming language that defines how a client may access a database. ...
Open Database Connectivity (ODBC) is a standard software API for connecting to database management systems (DBMS). ...
See also Client/Server is a network application architecture which separates the client (usually the graphical user interface) from the server. ...
A database dump contains a record of the table structure and/or the data from a database, and is usually in the form of a list of SQL queries. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
Data Manipulation Language (DML): is a family of computer languages used by computer programs or database users to retrieve, insert, delete and update data in a database. ...
Database normalization relates to the characterization of redundancy in a relational databases structure. ...
A deadlock is a situation wherein two or more competing actions are waiting for the other to finish, so neither ever does. ...
A deductive database system is a database system which can make deductions (ie: infer additional rules or facts) based on rules and facts stored in the (deductive) database. ...
A dimensional database is one which, rather than storing data in multiple two dimensional tables (as a relational databases does), represents key data entities as different dimensions. ...
A distributed database is a database that is under the control of a central database management system in which storage devices are not all attached to a common CPU. It may be stored in multiple computers located in the same physical location, or may be dispersed over a network of...
The entity-relationship model or entity-relationship diagram (ERD) is a data model or diagram for high-level descriptions of conceptual data models, and it provides a graphical notation for representing such data models in the form of entity-relationship diagrams. ...
A flat file database is described by a very simple database model, where all the information is stored in a plain text file, one database record per line. ...
A hierarchical database is a kind of database management system that links records together in a tree data structure such that each record type has only one owner, e. ...
A key field is a field of a database typically a relational database]]) table which together form a unique identifier for a database record (a table entry). ...
Main memory database systems provide direct access to data and the give the safety and convience of a traditional database system. ...
The MDH (Multi-Dimensional and Hierarchical) Database Toolkit is a Linux-based, open sourced, toolkit of portable software that supports very fast, flexible, multi-dimensional and hierarchical storage, retrieval and manipulation of information in data bases ranging in size up to 256 terabytes. ...
Multidimensional databases are variously (depending on the context) data aggregators which combine data from a multitude of data sources; databases which offer networks, hierarchies, arrays and other data formats difficult to model in SQL; or databases which offer a high degree of flexibility in the definition of dimensions, units, and...
OLAP is an acronym for online analytical processing. ...
A recordset is a Microsoft object oriented data structure that consists of a group of database records, and can either come from a base table or as the result of a query to the table. ...
A dynaset (short for dynamic set) is a set of data that is dynamically linked back to the database. ...
In computer file systems, a snapshot is a copy of a set of files and directories as they were at a particular point in the past. ...
The relational model for management of a database is a data model based on predicate logic and set theory. ...
SQL (short for Structured Query Language) is the most popular computer language used to create, modify and retrieve data from relational database management systems. ...
An object database is a database in which information is represented in the form of objects. ...
This is a list of important publications in computer science, organized by field. ...
Sometimes in databases redundant data is stored, e. ...
Software engineering is the profession that creates and maintains software applications by applying technologies and practices from computer science, project management, engineering, application domains, and other fields. ...
This list complements the software engineering article, giving more details and examples. ...
A temporal database is a database management system with built-in time aspects, e. ...
VLDB stands for Very Large DataBase. ...
References - The Codasyl Approach to Data Base Management. T. William Olle. Wiley, 1978. ISBN 0471995797
- Readings in Database Systems. Michael Stonebraker (ed). Morgan Kaufmann, 1988. (A collection of the most influential early papers on database technology from 1969 to 1988, with a preface analyzing their impact.)
- CNET News.com article, Study: Open-source databases going mainstream
- Sandro Nielsen: Lexicographical Basis for an Electronic Bilingual Accounting Dictionary: Theoretical Considerations
- Database @ sourceforge.net
- Open Source database comparison
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