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A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data manipulation language (DML) command. As SQL is a declarative programming language, SELECT queries specify a result set, but do not specify how to calculate it.
QUEL is a relational database query language, based on tuple relational calculus, with some similarities to SQL.It was created as a part of the Ingres DBMS effort at University of California, Berkeley, based on Codd's earlier suggested but not implemented Data Sub-Language ALPHA.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Example of QBE query with joins, designed in Borland's Paradox database. 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]
Model 204 is commonly used in government and military applications. [8] [9] [10]It was used commercially in the UK by Marks & Spencer. [citation needed] It was also used at the Ventura County Property Tax system in California, [11] the Harris County, Texas, Justice Information Management System, [12] and in the New York City Department of Education's Automate The Schools system.
Its database utilizes a hash-file system, enabling efficient data storage and retrieval by organizing data into dynamic associative arrays managed by associative files. Data within the Pick system is organized into a hierarchical structure of accounts, dictionaries, files, and sub-files based on a hash-table model with linear probing. This ...
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A database engine (or storage engine) is the underlying software component that a database management system (DBMS) uses to create, read, update and delete (CRUD) data from a database. Most database management systems include their own application programming interface (API) that allows the user to interact with their underlying engine without ...