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  2. Query by Example - Wikipedia

    en.wikipedia.org/wiki/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 . [ 1 ] It is the first graphical query language, using visual tables where the user would enter commands, example elements and conditions.

  3. Query language - Wikipedia

    en.wikipedia.org/wiki/Query_language

    A query language, also known as data query language or database query language (DQL), is a computer language used to make queries in databases and information systems. In database systems, query languages rely on strict theory to retrieve information. [1] A well known example is the Structured Query Language (SQL).

  4. Data query language - Wikipedia

    en.wikipedia.org/wiki/Data_query_language

    DQL statements are used for performing queries on the data within schema objects. The purpose of DQL commands is to get the schema relation based on the query passed to it. Although often considered part of DML, the SQL SELECT statement is strictly speaking an example of DQL. When adding FROM or WHERE data manipulators to the SELECT statement ...

  5. Online analytical processing - Wikipedia

    en.wikipedia.org/wiki/Online_analytical_processing

    In computing, online analytical processing, or OLAP (/ ˈ oʊ l æ p /), is an approach to quickly answer multi-dimensional analytical (MDA) queries. [1] The term OLAP was created as a slight modification of the traditional database term online transaction processing (OLTP). [2]

  6. Select (SQL) - Wikipedia

    en.wikipedia.org/wiki/Select_(SQL)

    Queries allow the user to describe desired data, leaving the database management system (DBMS) to carry out planning, optimizing, and performing the physical operations necessary to produce that result as it chooses. A query includes a list of columns to include in the final result, normally immediately following the SELECT keyword.

  7. Nested set model - Wikipedia

    en.wikipedia.org/wiki/Nested_set_model

    The nested set model is a technique for representing nested set collections (also known as trees or hierarchies) in relational databases.. It is based on Nested Intervals, that "are immune to hierarchy reorganization problem, and allow answering ancestor path hierarchical queries algorithmically — without accessing the stored hierarchy relation".

  8. Object database - Wikipedia

    en.wikipedia.org/wiki/Object_database

    An object database or object-oriented database is a database management system in which information is represented in the form of objects as used in object-oriented programming. Object databases are different from relational databases which are table-oriented.

  9. Query evaluation - Wikipedia

    en.wikipedia.org/wiki/Query_evaluation

    The data complexity is the computational complexity when the query is fixed and when the input is just the database. For instance, we say that query evaluation has polynomial-time data complexity for a class of queries if, for every fixed query Q in that class, given a database D, we can compute the answers to Q on D in polynomial time.