A database, often abbreviated as DB, is a collection of information organized in such a way that a computer program can quickly select desired pieces of data. Fields, Records and Files You can think of a traditional database as an electronic filing systemorganized by fieldsrecordsand files. A field is a single piece of information; a record is one complete set of fields; and a file is a collection of records.
Database machine In the s and s, attempts were made to build database systems with integrated hardware and software. The underlying philosophy was that such integration would provide higher performance at lower cost. In the long term, these efforts were generally unsuccessful because specialized database machines could not keep pace with the rapid development and progress of general-purpose computers.
Thus most database systems nowadays are software systems running on general-purpose hardware, using general-purpose computer data storage. However this idea is still pursued for certain applications by some companies like Netezza and Oracle Exadata.
Subsequent multi-user versions were tested by customers in andby which time a standardized query language — SQL[ citation needed ] — had been added. PostgreSQL is often used for global mission critical applications the. Inthis project was consolidated into an independent enterprise.
Another data model, the entity—relationship modelemerged in and gained popularity for database design as it emphasized a more familiar description than the earlier relational model.
Later on, entity—relationship constructs were retrofitted as a data modeling construct for the relational model, and the difference between the two have become irrelevant. The new computers empowered their users with spreadsheets like Lotus and database software like dBASE.
The dBASE product was lightweight and easy for any computer user to understand out of the box. The data manipulation is done by dBASE instead of by the user, so the user can concentrate on what he is doing, rather than having to mess with the dirty details of opening, reading, and closing files, and managing space allocation.
Programmers and designers began to treat the data in their databases as objects. This allows for relations between data to be relations to objects and their attributes and not to individual fields.
Object databases and object-relational databases attempt to solve this problem by providing an object-oriented language sometimes as extensions to SQL that programmers can use as alternative to purely relational SQL. On the programming side, libraries known as object-relational mappings ORMs attempt to solve the same problem.
XML databases are mostly used in applications where the data is conveniently viewed as a collection of documents, with a structure that can vary from the very flexible to the highly rigid: NoSQL databases are often very fast, do not require fixed table schemas, avoid join operations by storing denormalized data, and are designed to scale horizontally.
In recent years, there has been a strong demand for massively distributed databases with high partition tolerance, but according to the CAP theorem it is impossible for a distributed system to simultaneously provide consistencyavailability, and partition tolerance guarantees.
A distributed system can satisfy any two of these guarantees at the same time, but not all three. For that reason, many NoSQL databases are using what is called eventual consistency to provide both availability and partition tolerance guarantees with a reduced level of data consistency.
NewSQL is a class of modern relational databases that aims to provide the same scalable performance of NoSQL systems for online transaction processing read-write workloads while still using SQL and maintaining the ACID guarantees of a traditional database system.
This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. March Learn how and when to remove this template message Databases are used to support internal operations of organizations and to underpin online interactions with customers and suppliers see Enterprise software.
Databases are used to hold administrative information and more specialized data, such as engineering data or economic models. Examples include computerized library systems, flight reservation systemscomputerized parts inventory systemsand many content management systems that store websites as collections of webpages in a database.
Classification[ edit ] One way to classify databases involves the type of their contents, for example: Another way is by their application area, for example: A third way is by some technical aspect, such as the database structure or interface type.
This section lists a few of the adjectives used to characterize different kinds of databases. An in-memory database is a database that primarily resides in main memorybut is typically backed-up by non-volatile computer data storage.
Main memory databases are faster than disk databases, and so are often used where response time is critical, such as in telecommunications network equipment. An active database includes an event-driven architecture which can respond to conditions both inside and outside the database.
Possible uses include security monitoring, alerting, statistics gathering and authorization. Many databases provide active database features in the form of database triggers.
A cloud database relies on cloud technology. Both the database and most of its DBMS reside remotely, "in the cloud", while its applications are both developed by programmers and later maintained and used by end-users through a web browser and Open APIs.
Data warehouses archive data from operational databases and often from external sources such as market research firms. The warehouse becomes the central source of data for use by managers and other end-users who may not have access to operational data. For example, sales data might be aggregated to weekly totals and converted from internal product codes to use UPCs so that they can be compared with ACNielsen data.
Some basic and essential components of data warehousing include extracting, analyzing, and mining data, transforming, loading, and managing data so as to make them available for further use. A deductive database combines logic programming with a relational database.PubMed comprises more than 28 million citations for biomedical literature from MEDLINE, life science journals, and online books.
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Also read about efforts to halt sexual harassment in . We would like to show you a description here but the site won’t allow us. A database is a collection of information that is organized so that it can be easily accessed, managed and updated..
Data is organized into rows, columns and tables, and it is indexed to make it easier to find relevant information.