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Encyclopedia > Database

A database is a structured collection of records or data. A computer database relies upon software to organize the storage of data. The software models the database structure in what are known as database models. The model in most common use today is the relational model. Other models such as the hierarchical model and the network model use a more explicit representation of relationships (see below for explanation of the various database models). A database management system (DBMS) is computer software designed for the purpose of managing databases based on a variety of data models. ... For other uses, see Structure (disambiguation). ... For other uses, see Data (disambiguation). ... This article is about the machine. ... Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ... A database model is a theory or specification describing how a database is structured and used. ... The relational model for database management is a database model based on predicate logic and set theory. ... In a hierarchical data model, data are organized into a tree-like structure. ... The network model is a database model conceived as a flexible way of representing objects and their relationships. ...


Database management systems (DBMS) are the software used to organize and maintain the database. These are categorized according to the database model that they support. The model tends 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. A database model is a theory or specification describing how a database is structured and used. ...

Contents

History

The earliest known use of the term data base was in November 1963, when the System Development Corporation sponsored a symposium under the title Development and Management of a Computer-centered Data Base[1]. 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. (The abbreviation DB, however, survives.) System Development Corporation, based in Los Angeles, California, was spun off from RAND Corporation in 1957. ...


The first database management systems were developed in the 1960s''''Bold text''''Bold text''''.'

 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. While IMS along with the CODASYL IDMS were the big, high visibility databases developed in the 1960s, several others were also born in that decade, some of which have a significant installed base today. Two worthy of mention are the PICK and MUMPS databases, with the former developed originally as an operating system with an embedded database and the latter as a programming language and database for the development of healthcare systems. 

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 products (IDMS) and network model products (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. Charles W. Bachman is a prominent computer scientist, particularly in the area of databases. ... Punched cards (or Hollerith cards, or IBM cards), are pieces of stiff paper that contain digital information represented by the presence or absence of holes in predefined positions. ... Compact audio cassette Magnetic tape is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. ... A data model is a model that describes how data are represented and used in an abstract way. ... 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 flexible way of representing objects and their relationships. ... In a hierarchical data model, data are organized into a tree-like structure. ... 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. ... For other uses, see IBM (disambiguation) and Big Blue. ... Information Management System (IMS) is a joint hierarchical database and information management system. ... IDMS (Integrated Database Management System) is a (network) CODASYL database management system first developed at B.F. Goodrich and later marketed by Cullinane Database Systems (renamed Cullinet in 1983). ... The Pick operating system (often called just the Pick system or simply Pick) is a demand-paged, multiuser, virtual memory, time-sharing operating system based around a unique multivalued database. ... The relational model for database management is a database model based on predicate logic and set theory. ... Edgar Frank Ted Codd (August 23, 1923 – April 18, 2003) was a British computer scientist who made seminal contributions to the theory of relational databases. ... Michael Stonebraker is a computer scientist specializing in database research and development. ... Ingres (pronounced ingress) is a commercially supported, open-source relational database management system. ... Sather Tower (the Campanile) looking out over the San Francisco Bay and Mount Tamalpais. ... System R is a database system built as a research project at IBM San Jose Research (now IBM Almaden Research Center) in the 1970s. ... The term Oracle database may refer either to the database management system (DBMS) software released by Oracle Corporation as Oracle RDBMS, or to any of the individual databases managed by such software. ... DB2 is one of IBMs lines of relational database management system (or, as IBM now calls it, data server) software products within IBMs broader Information Management Software line. ... dBASE III The correct title of this article is dBASE. The initial letter is capitalized because of technical restrictions. ... CP/M is an operating system originally created for Intel 8080/85 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. 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. A distributed database is a database that is under the control of a central database management system (DBMS) 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... A database machine or back end processor is a computer or special hardware that stores and retrieves data from a database. ...


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 easily cope with, such as spatial databases, engineering data (including software 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 1990s also saw the spread of Open Source databases, such as PostgreSQL and MySQL. An OODBMS (object-oriented database management system) is a system offering DBMS facilities in an object-oriented programming environment. ... A spatial database is a database that is optimized to store and query data related to objects in space, including points, lines and polygons. ... A software repository is a storage location from which software packages may be be retrieved and installed on a computer. ... Open source refers to projects that are open to the public and which draw on other projects that are freely available to the general public. ... PostgreSQL is a free software object-relational database management system (ORDBMS), released under a BSD-style license. ... MySQL (pronounced (IPA) , my S-Q-L[1]) is a multithreaded, multi-user SQL database management system (DBMS)[2] which has, according to MySQL AB, more than 10 million installations. ...


In the 2000s, the fashionable area for innovation is the XML database. As with object databases, this has spawned a new collection of start-up 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. An XML database is a data persistence software system that allows data to be imported, accessed and exported in the XML format. ...


Database models

Main article: 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. Here are three examples: 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. ... In mathematics, model theory is the study of the representation of mathematical concepts in terms of set theory, or the study of the models which underlie mathematical systems. ...


Hierarchical model

In a hierarchical model, data is organized into an inverted tree-like structure, implying a multiple downward link in each node to describe the nesting, and a sort field to keep the records in a particular order in each same-level list. This structure arranges the various data elements in a hierarchy and helps to establish logical relationships among data elements of multiple files. Each unit in the model is a record which is also known as a node. In such a model, each record on one level can be related to multiple records on the next lower level. A record that has subsidiary records is called a parent and the subsidiary records are called children. Data elements in this model are well suited for one-to-many relationships with other data elements in the database. In a hierarchical data model, data are organized into a tree-like structure. ...


This model is advantageous when the data elements are inherently hierarchical. The disadvantage is that in order to prepare the database it becomes necessary to identify the requisite groups of files that are to be logically integrated. Hence, a hierarchical data model may not always be flexible enough to accommodate the dynamic needs of an organization.


Network model

The network model tends to store records with links to other records. Each record in the database can have multiple parents, i.e., the relationships among data elements can have a many to many relationship. Associations are tracked via "pointers". These pointers can be node numbers or disk addresses. Most network databases tend to also include some form of hierarchical model. Databases can be translated from hierarchical model to network and vice versa. The main difference between the network model and hierarchical model is that in a network model, a child can have a number of parents whereas in a hierarchical model, a child can have only one parent. The network model is a database model conceived as a flexible way of representing objects and their relationships. ...


The network model provides greater advantage than the hierarchical model in that it promotes greater flexibility and data accessibility, since records at a lower level can be accessed without accessing the records above them. This model is more efficient than hierarchical model, easier to understand and can be applied to many real world problems that require routine transactions. The disadvantages are that: It is a complex process to design and develop a network database; It has to be refined frequently; It requires that the relationships among all the records be defined before development starts, and changes often demand major programming efforts; Operation and maintenance of the network model is expensive and time consuming.


Examples of database engines that have network model capabilities are RDM Embedded and RDM Server.


Relational model

Main article: Relational Model

The basic data structure of the relational model is a table where information about a particular entity (say, an employee) is represented in columns and rows. The columns enumerate the various attributes of an entity (e.g. employee_name, address, phone_number). Rows (also called records) represent instances of an entity (e.g. specific employees). The relational model for database management is a database model based on predicate logic and set theory. ...


The "relation" in "relational database" comes from the mathematical notion of relations from the field of set theory. A relation is a set of tuples, so rows are sometimes called tuples. All tables in a relational database adhere to three basic rules. In mathematics, the concept of a relation is a generalization of 2-place relations, such as the relation of equality, denoted by the sign = in a statement like 5 + 7 = 12, or the relation of order, denoted by the sign < in a statement like 5 < 12. Relations that involve two... Set theory is the mathematical theory of sets, which represent collections of abstract objects. ... In mathematics, a tuple is a finite sequence (also known as an ordered list) of objects, each of a specified type. ...

  • The ordering of columns is immaterial
  • Identical rows are not allowed in a table
  • Each row has a single (separate) value for each of its columns (each tuple has an atomic value).

If the same value occurs in two different records (from the same table or different tables) it can imply a relationship between those records. Relationships between records are often categorized by their cardinality (1:1, (0), 1:M, M:M).


Tables can have a designated column or set of columns that act as a "key" to select rows from that table with the same or similar key values. A "primary key" is a key that has a unique value for each row in the table. Keys are commonly used to join or combine data from two or more tables. For example, an employee table may contain a column named address which contains a value that matches the key of a address table. Keys are also critical in the creation of indexes, which facilitate fast retrieval of data from large tables. 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.


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 applications, such as Wikipedia, perform SQL queries when generating pages. In general, a query is a form of questioning, in a line of inquiry. ... SQL (IPA: or ) is a computer language designed for the retrieval and management of data in relational database management systems, database schema creation and modification, and database object access control management. ... Wikipedia (IPA: , or ( ) is a multilingual, web-based, free content encyclopedia project, operated by the Wikimedia Foundation, a non-profit organization. ...


In response to a query, the database returns a result set, which is the list of rows constituting the answer. 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 are combined into one, by doing a join. There are a number of relational operations in addition to join. A JOIN clause in SQL combines records from two tables in a relational database and results in a new (temporary) table, also called a joined table. Structured Query Language (SQL:2003) specifies two types of joins: inner and outer. ...


Normal forms

Relations are classified based upon the types of anomalies to which they're vulnerable. A database that's in the first normal form is vulnerable to all types of anomalies, while a database that's in the domain/key normal form has no modification anomalies. Normal forms are hierarchical in nature. That is, the lowest level is the first normal form, and the database cannot meet the requirements for higher level normal forms without first having met all the requirements of the lesser normal form. Database normalization, sometimes referred to as canonical synthesis, is a technique for designing relational database tables to minimize duplication of information and, in so doing, to safeguard the database against certain types of logical or structural problems, namely data anomalies. ...


Database Management Systems

A database management system (DBMS) is computer software designed for the purpose of managing databases based on a variety of data models. ...

Relational database management systems

An RDBMS implements the features of the relational model outlined above. In this context, Date's Information Principle states: Christopher J. Date is an independent author, lecturer, researcher, and consultant, specializing in relational database technology. ...

The entire information content of the database is represented in one and only one way. Namely as explicit values in column positions (attributes) and rows in relations (tuples) Therefore, there are no explicit pointers between related tables. In mathematics, a tuple is a finite sequence (also known as an ordered list) of objects, each of a specified type. ...

Post-relational database models

Several products have been identified as post-relational because the data model incorporates relations but is not constrained by the Information Principle, requiring that all information is represented by data values in relations. Products using a post-relational data model typically employ a model that actually pre-dates the relational model. These might be identified as a directed graph with trees on the nodes. In mathematics, a relation is a generalization of arithmetic relations such as = and < which occur in statements such as 5 < 6 or 2 + 2 = 4. See relation (mathematics), binary relation and relational algebra. ... The relational model for database management is a database model based on predicate logic and set theory. ... This article just presents the basic definitions. ... In computer science, a tree is a widely-used computer data structure that emulates a tree structure with a set of linked nodes. ... A binary tree, a simple type of branching linked data structure. ...


Examples of models that could be classified as post-relational are PICK aka MultiValue, and MUMPS. The Pick operating system (often called just the Pick system or simply Pick) is a demand-paged, multiuser, virtual memory, time-sharing operating system based around a unique multivalued database. ... It has been suggested that this article or section be merged with Dimensional database. ...


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. ... In an object database (also object oriented database), information is represented in the form of objects as used in object-oriented programming. ... In computer science, a type system defines how a programming language classifies values and expressions into types, how it can manipulate those types and how they interact. ... This article does not cite any references or sources. ... Encapsulation may refer to: information hiding and separation of concerns, in software engineering, the process of enclosing programming elements inside larger, more abstract entities integrated circuit encapsulation, in electronics the design and manufacture of protective packages micro-encapsulation, means to confine material molecular encapsulation, means to confine molecules encapsulation (pharmacology... In computer science, polymorphism means allowing a single definition to be used with different types of data (specifically, different classes of objects). ...


A variety of these 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 capabilities as well as traditional query facilities. It has been suggested that Orthogonal persistence be merged into this article or section. ...


DBMS internals

Storage and physical database design

Database tables/indexes are typically stored in memory or on hard disk in one of many forms, ordered/unordered flat files, ISAM, heaps, hash buckets or B+ trees. These have various advantages and disadvantages discussed further in the main article on this topic. The most commonly used are B+ trees and ISAM. Database tables/indexes are typically stored in memory or on hard disk in one of many forms, ordered/unordered Flat files, ISAM, Heaps, Hash buckets or B+ Trees. ... Image File history File links This is a lossless scalable vector image. ... A simple diagram depicting conversion of a CSV-format flat file database table into a relational database table. ... ISAM stands for Indexed Sequential Access Method, a method for storing data for fast retrieval. ... Example of a complete binary max heap In computer science, a heap is a specialized tree-based data structure that satisfies the heap property: if B is a child node of A, then key(A) ≥ key(B). ... In computer science, a hash table is a data structure that speeds up searching for information by a particular aspect of that information, called a key. ... A simple B+ tree example linking the keys 1-7 to data values d1-d7. ...


Other important design choices relate to the clustering of data by category (such as grouping data by month, or location), creating pre-computed views known as materialized views, partitioning data by range or hash. As well memory management and storage topology can be important design choices for database designers. Just as normalization is used to reduce storage requirements and improve the extensibility of the database, conversely denormalization is often used to reduce join complexity and reduce execution time for queries. [2]


Indexing

All of these databases can take advantage of indexing to increase their speed. 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. Typically, indexes are also stored in the various forms of data-structure mentioned above (such as B-trees, hashes, and linked lists). Usually, a specific technique is chosen by the database designer to increase efficiency in the particular case of the type of index required. A database index is a data structure that improves the speed of operations in a table. ... B-trees are tree data structures that are most commonly found in databases and filesystem implementations. ... In computer science, a hash table is a data structure that speeds up searching for information by a particular aspect of that information, called a key. ... In computer science, a linked list is one of the fundamental data structures used in computer programming. ...


Relational DBMS's have the advantage that indexes can be created or dropped without changing existing applications making use of it. The database chooses between many different strategies based on which one it estimates will run the fastest. In other words, indexes are transparent to the application or end-user querying the database; while they affect performance, any SQL command will run with or without index to compute the result of an SQL statement. The RDBMS will produce a plan of how to execute the query, which is generated by analyzing the run times of the different algorithms and selecting the quickest. Some of the key algorithms that deal with joins are nested loop join, sort-merge join and hash join. Which of these is chosen depends on whether an index exists, what type it is, and its cardinality. SQL (IPA: or ) is a computer language designed for the retrieval and management of data in relational database management systems, database schema creation and modification, and database object access control management. ... A JOIN clause in SQL combines records from two tables in a relational database and results in a new (temporary) table, also called a joined table. Structured Query Language (SQL:2003) specifies two types of joins: inner and outer. ... The naive algorithm that joins two relations and by making two nested loops: For each tuple in R as r do For each tuple in S as s do If r and s satisfy the join condition Then output the tuple <r,s> The algorithm runs in I/Os, where... 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. ...


An index speeds up access to data, but it has disadvantages as well. First, every index increases the amount of storage on the hard drive necessary for the database file, and second, the index must be updated each time the data are altered, and this costs time. (Thus an index saves time in the reading of data, but it costs time in entering and altering data. It thus depends on the use to which the data are to be put whether an index is on the whole a net plus or minus in the quest for efficiency.)


A special case of an index is a primary index, or primary key, which is distinguished in that the primary index must ensure a unique reference to a record. Often, for this purpose one simply uses a running index number (ID number). Primary indexes play a significant role in relational databases, and they can speed up access to data considerably.


Transactions and concurrency

In addition to their data model, most practical databases ("transactional databases") attempt to enforce a database transaction . 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. ... For other uses, see acid (disambiguation). ...

  • 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, atomicity implies indivisibility and irreducibility, so an atomic operation must appear to be performed entirely or not at all. ... In database systems, a consistent transaction is one that does not violate any integrity contraints during its execution. ... Look up isolation in Wiktionary, the free dictionary. ... In database systems, 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. ... In databases and transaction processing, serializability is the property of a schedule being serializable. ... In databases and transaction processing, serializability is the property of a schedule being serializable. ...


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 real time. 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 are calculated by querying a "majority" of replicas.
  • Multimaster: Two or more replicas sync each other via a transaction identifier.

Parallel synchronous replication of databases enables transactions to be replicated on multiple servers simultaneously, which provides a method for backup and security as well as data availability.


Security

Database security denotes the system, processes, and procedures that protect a database from unintended activity. Database security is the system, processes, and procedures that protect a database from unintended activity. ...


In the United Kingdom legislation protecting the public from unauthorized disclosure of personal information held on databases falls under the Office of the Information Commissioner. United Kingdom based organizations holding personal data in electronic format (databases for example) are required to register with the Data Commissioner. (reference: [1])


Locking

Locking is the act of putting a lock (access restriction) on an aspect of a database which at a particular given instance is being modified. Such locks can be applied on a row level, or on other levels such as an entire table. This helps maintain the integrity of the data by ensuring that only one user at a time can modify the data. Databases can also be locked for other reasons, like access restrictions for given levels of user. Image File history File links This is a lossless scalable vector image. ... In computer science, a lock is a synchronization mechanism for enforcing limits on access to a resource in an environment where there are many threads of execution. ...


Databases are also locked for routine database maintenance, which prevents changes being made during the maintenance. See IBM for more detail.


Architecture

Depending on the intended use, there are a number of database architectures in use. Many databases use a combination of strategies. On-line Transaction Processing systems (OLTP) often use a row-oriented datastore architecture, while data-warehouse and other retrieval-focused applications like Google's BigTable, or bibliographic database(library catalogue) systems may use a column-oriented datastore architecture. This article is about the corporation. ... BigTable is a compressed, high performance and proprietary database built on Google File System (GFS), Chubby Lock Service and a few other Google programs; it is currently not distributed or used outside of Google. ...


Document-Oriented, XML, Knowledgebases, as well as frame databases and rdf-stores (aka Triple-Stores), may also use a combination of these architectures in their implementation.


Finally it should be noted that not all database have or need a database 'schema' (so called schema-less databases).


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, 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 to retrieve the information stored in a database. Two commonly used database APIs are JDBC and ODBC. Software redirects here. ... Application software is a subclass of computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform. ... API redirects here. ... 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). ...


For example suppliers database contains the data relating to suppliers such as;

  • supplier name
  • supplier code
  • supplier address

It is often used by schools to teach students and grade them.


Links to DBMS products

Main article: :Category:Database management systems

4th Dimension (or 4D) is a relational database management system and integrated IDE developed by Laurent Ribardière in 1984. ... Adabas is Software AG’s advanced database management system. ... Alpha Five is a database application produced by Alpha Software, similar to Microsoft Access and Filemaker Pro. ... Apache Derby is a Java-based Relational Database Management System that can be embedded in Java programs and used for online transaction processing (OLTP). ... Berkeley DB (DB) is a high-performance, embedded database library with C, C++, Java, Perl, Python, Tcl and many other language bindings. ... CouchDB (previously called CouchDb) is a free software RESTful document-oriented database written in Erlang. ... An editor has expressed a concern that the subject of the article does not satisfy the notability guideline or one of the following guidelines for inclusion on Wikipedia: Biographies, Books, Companies, Fiction, Music, Neologisms, Numbers, Web content, or several proposals for new guidelines. ... dBASE III The correct title of this article is dBASE. The initial letter is capitalized because of technical restrictions. ... FileMaker Pro is a cross-platform database application from FileMaker Inc. ... Firebird (sometimes called FirebirdSQL) is a relational database management system offering many ANSI SQL-2003 features. ... H2 is a relational database management system written in Java. ... HSQL Database Manager HSQLDB is a relational database management system written in Java. ... DB2 is one of IBMs lines of relational database management system (or, as IBM now calls it, data server) software products within IBMs broader Information Management Software line. ... Information Management System (IMS) is a joint hierarchical database and information management system. ... UniVerse is an example of dimensional database also known as a multi-value database system which runs on Windows and most major Unix and Linux releases. ... Informix is a family of relational database management system products from IBM, acquired in 2001 from a company (also called Informix or Informix Software) which dates its origins back to 1980. ... Ingres (pronounced ingress) is a commercially supported, open-source relational database management system. ... InterBase is a relational database management system (RDBMS) currently developed and marketed by CodeGear. ... Caché is a proprietary M technology-based database management system from InterSystems. ... MaxDB is an ANSI SQL-92 (entry level) compliant relational database management system (RDBMS) from SAP AG, which was delivered also by MySQL AB from 2003 to 2007. ... Microsoft Office Access, previously known as Microsoft Access, is a relational database management system from Microsoft that combines the relational Microsoft Jet Database Engine with a graphical user interface and software development tools. ... Microsoft SQL Server is a relational database management system (RDBMS) produced by Microsoft. ... Model 204 is a database system for IBM and compatible mainframes, running under OS/390. ... MySQL (pronounced (IPA) , my S-Q-L[1]) is a multithreaded, multi-user SQL database management system (DBMS)[2] which has, according to MySQL AB, more than 10 million installations. ... NOMAD was developed by National CSS, Inc, in Stamford (later Wilton), CT, starting in 1973. ... Objectivity/DB is a commercial object oriented database management system ODBMS produced by Objectivity, Inc. ... ObjectStore is a commercial object database, which is a specialized type of database designed to handle data created by applications that use object-oriented programming techniques. ... The current version of the article or section reads like an advertisement. ... OpenOffice. ... The term Oracle database may refer either to the database management system (DBMS) software released by Oracle Corporation as Oracle RDBMS, or to any of the individual databases managed by such software. ... Paradox is a relational database management system currently published by Corel Corporation. ... PostgreSQL is a free software object-relational database management system (ORDBMS), released under a BSD-style license. ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ... SQLite is a mostly ACID-compliant relational database management system contained in a relatively small (~500kb) C programming library. ... Superbase is an end-user desktop database program that started on the Commodore PET and was ported from that to various operating systems over the course of more than 20 years. ... Sybase Inc. ... Teradata Teradata Corporation (NYSE: TDC) is the global leader in data warehousing and analytic technologies. ... Vertica Systems (www. ... VFP redirects here. ...

References

Notes
  1. ^ Swanson, Kenneth (1963-11-08). Development and Management of a Computer-Centered Database. dtic.mil. Retrieved on 2007-07-20.
  2. ^ S. Lightstone, T. Teorey, T. Nadeau, Physical Database Design: the database professional's guide to exploiting indexes, views, storage, and more, Morgan Kaufmann Press, 2007. ISBN 0123693896
Bibliography
  • Connolly, Thomas, and Caroln Begg. Database Systems. New York: Harlow, 2002.
  • Date, C. J. An Introduction to Database Systems, Eighth Edition, Addison Wesley, 2003.
  • Galindo, J., Urrutia, A., Piattini, M., Fuzzy Databases: Modeling, Design and Implementation (FSQL guide). Idea Group Publishing Hershey, USA, 2006.
  • Galindo, J., Ed. Handbook on Fuzzy Information Processing in Databases. Hershey, PA: Information Science Reference (an imprint of Idea Group Inc.), 2008.
  • Gray, J. and Reuter, A. Transaction Processing: Concepts and Techniques, 1st edition, Morgan Kaufmann Publishers, 1992.
  • Kroenke, David M. Database Processing: Fundamentals, Design, and Implementation (1997), Prentice-Hall, Inc., pages 130-144.
  • Kroenke, David M., and David J. Auer. Database Concepts. 3rd ed. New York: Prentice, 2007.
  • Lightstone, S., T. Teorey, and T. Nadeau, Physical Database Design: the database professional's guide to exploiting indexes, views, storage, and more, Morgan Kaufmann Press, 2007. ISBN 0-12369-389-6.
  • Shih, J. "Why Synchronous Parallel Transaction Replication is Hard, But Inevitable?", white paper, 2007.
  • Teorey, T.; Lightstone, S. and Nadeau, T. Database Modeling & Design: Logical Design, 4th edition, Morgan Kaufmann Press, 2005. ISBN 0-12-685352-5
  • Tukey, John W. Exploratory Data Analysis. Reading, MA: Addison Wesley, 1977.

Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 201st day of the year (202nd in leap years) in the Gregorian calendar. ...

See also

The following tables compare general and technical information for a number of relational database management systems. ... Database-centric architecture is a term that has several distinct meanings, all of which relate to software architectures in which databases play a crucial role. ... A database is an information set with a regular structure. ... Government databases collect personal information for various reasons (mass surveillance, Schengen Information System in the European Union, Social Security, statistics, etc. ... Since the beginning of scientific glass research in the 19th century thousands of glass property-composition datasets were published in the scientific literature, in patents, and other sources. ... An online database is a database accessible via a network, now generally the internet. ... // A real-time database is a processing system designed to handle workloads whose state is constantly changing (Buchmann). ...

External links

A database management system (DBMS) is computer software designed for the purpose of managing databases based on a variety of data models. ... 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. ... Database normalization, sometimes referred to as canonical synthesis, is a technique for designing relational database tables to minimize duplication of information and, in so doing, to safeguard the database against certain types of logical or structural problems, namely data anomalies. ... Database tables/indexes are typically stored in memory or on hard disk in one of many forms, ordered/unordered Flat files, ISAM, Heaps, Hash buckets or B+ Trees. ... According to Elmasri and Navathe (2004, p. ... An example of a database that has not enforced referential integrity. ... Relational algebra, an offshoot of first-order logic, is a set of relations closed under operators. ... The relational calculus refers to the two calculi, the tuple calculus and the domain calculus, that are part of the relational model for databases and that provide a declarative way to specify database queries. ... A relational database is a database that conforms to the relational model, and refers to a databases data and schema (the databases structure of how those data are arranged). ... A relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model as introduced by E. F. Codd. ... The relational model for database management is a database model based on predicate logic and set theory. ... An object-relational database (ORD) or object-relational database management system (ORDBMS) provides a relational database management system that allows developers to integrate a database with their own custom data-types and methods. ... In computer science, transaction processing is information processing that is divided into individual, indivisible operations, called Each transaction must succeed or fail as a complete unit; it cannot remain in an intermediate state. ... For other uses, see acid (disambiguation). ... The Greek lowercase omega (ω) character is historically used by academics to represent Null in relational databases. ... In the relational model a candidate key of a relation variable (relvar) is a set of attributes of that relvar such that (1) at all times it holds in the relation assigned to that variable that there are no two distinct tuples with the same values for these attributes and... In the context of relational databases, a foreign key is a referential constraint between two tables[1]. The foreign key identifies a column or a set of columns in one (referencing) table that refers to a column or set of columns in another (referenced) table. ... In database design, a primary key is a value that can be used to identify a unique row in a table. ... A superkey is defined in the relational model as a set of attributes of a relation variable (relvar) for which it holds that in all relations assigned to that variable there are no two distinct tuples (rows) that have the same values for the attributes in this set. ... A surrogate key is a unique primary key generated by the relational database management system that is not derived from any data in the database and whose only significance is to act as the primary key. ... A database trigger is procedural code that is automatically executed in response to certain events on a particular table in a database. ... In database theory, a view is a virtual or logical table composed of the result set of a query. ... In relational databases, SQL databases, and flat file databases, a table is a set of data elements (values) that is organized using a model of horizontal rows and vertical columns. ... In database packages, the term cursor refers to a control structure for the successive traversal (and potential processing) of records in a result set as returned by a query. ... In in the field of databases in computer science, a transaction log (also database log or binary log) is a history of actions executed by a database management system to guarantee ACID properties over crashes or hardware failures. ... 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. ... A database index is a data structure that improves the speed of operations in a table. ... A stored procedure is a subroutine available to applications accessing a relational database system. ... A partition is a division of a logical database or its constituting elements into distinct independent parts. ... SQL (IPA: or ) is a computer language designed for the retrieval and management of data in relational database management systems, database schema creation and modification, and database object access control management. ... An SQL SELECT statement returns a result set of records from one or more tables. ... A SQL INSERT statement adds one or more records to a table in a relational database. ... An UPDATE statement in SQL changes data in one or more records in a relational database management system. ... Wikipedia does not have an article with this exact name. ... An SQL DELETE statement removes one or more records from a table. ... A JOIN clause in SQL combines records from two tables in a relational database and results in a new (temporary) table, also called a joined table. Structured Query Language (SQL:2003) specifies two types of joins: inner and outer. ... In SQL the UNION operator combines the results of two SQL queries into a single table of all matching rows. ... A CREATE statement in SQL creates an object inside of a relational database management system (RDBMS). ... A DROP statement in SQL removes an object from a relational database management system (RDBMS). ... It has been suggested that this article or section be merged into Database transaction. ... A COMMIT statement in SQL ends a transaction within a relational database management system (RDBMS) and makes all changes visible to other users. ... In database technologies, a rollback is an operation which returns the database to some previous state. ... The Truncate statement removes all the data from a table. ... An ALTER statement in SQL changes the properties of an object inside of a relational database management system (RDBMS). ... A relational database is a database that conforms to the relational model, and refers to a databases data and schema (the databases structure of how those data are arranged). ... A simple diagram depicting conversion of a CSV-format flat file database table into a relational database table. ... 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 representing data in multiple relations (as a relational database does), represents key data entities as different dimensions. ... In a hierarchical data model, data are organized into a tree-like structure. ... The network model is a database model conceived as a flexible way of representing objects and their relationships. ... In an object database (also object oriented database), information is represented in the form of objects as used in object-oriented programming. ... An object-relational database (ORD) or object-relational database management system (ORDBMS) provides a relational database management system that allows developers to integrate a database with their own custom data-types and methods. ... A temporal database is a database management system with built-in time aspects, e. ... An XML database is a data persistence software system that allows data to be imported, accessed and exported in the XML format. ... 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. ... A data dictionary is a set of metadata that contains definitions and representations of data elements. ... JDBC is an API for the Java programming language that defines how a client may access a database. ... In computing, Open Database Connectivity (ODBC) provides a standard software API method for using database management systems (DBMS). ... Query languages are computer languages used to make queries into databases and information systems. ... 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. ... A query plan (or query execution plan) is an set of steps used to access information in a SQL relational database management system. ... The following is a list of object-oriented database management systems. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... See DBMS for a shorter list of “typical”, representative database management systems. ... The following tables compare general and technical information for a number of relational database management systems. ...

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