Data retrieval means obtaining data from a
Database Management System
In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases ...
(DBMS) such as
ODBMS. In this case, it is considered that data is represented in a
structured way, and there is no
ambiguity
Ambiguity is the type of meaning in which a phrase, statement or resolution is not explicitly defined, making several interpretations plausible. A common aspect of ambiguity is uncertainty. It is thus an attribute of any idea or statement ...
in data.
In order to retrieve the desired data the user present a set of criteria by a query. Then the DBMS selects the demanded data from the database. The retrieved data may be stored in a file, printed, or viewed on the screen.
A ''query language'', such as ''
Structured Query Language'' (SQL), is used to prepare the queries. SQL is an
American National Standards Institute
The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The orga ...
(ANSI) standardized query language developed specifically to write database queries. Each DBMS may have its own language, but most relational .
How the data is presented
Reports and queries are the two primary forms of the retrieved data from a database. There are some overlaps between them, but queries generally select a relatively small portion of the database, while reports show larger amounts of data. Queries also present the data in a standard format and usually display it on the monitor; whereas reports allow formatting of the output however you like and is normally printed.
Reports are designed using a report generator built into the DBMS.
See also
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Database model
A database model is a type of data model that determines the logical structure of a database. It fundamentally determines in which manner data can be stored, organized and manipulated. The most popular example of a database model is the relation ...
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Data maintenance
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Relational database
A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relati ...
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Query by Example
Query by Example (QBE) is a database query language for relational databases. It was devised by Moshé M. Zloof at IBM Research during the mid-1970s, in parallel to the development of SQL. It is the first graphical query language, using visual ...
References
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External links
SQL StatementsSQL Statements Tutorial
SQL Tutorial at W3Schools
{{DEFAULTSORT:Data Retrieval
Database management systems
Relational database management systems