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 . QUEL was used for a short time in most products based on the freely available Ingres source code, most notably in an implementation called POSTQUEL supported by POSTGRES . As Oracle and DB2 gained market share in the early 1980s, most companies then supporting QUEL moved to SQL instead. QUEL continues to be available as a part of the Ingres DBMS, although no QUEL-specific language enhancements have been added for many years.
6-625: [REDACTED] Look up quel in Wiktionary, the free dictionary. Quel may refer to: QUEL query languages , a relational database access language Quel, La Rioja , a municipality in La Rioja, Spain Quél , taxonomic author abbreviation for Lucien Quélet (1832–1899), French naturalist and mycologist Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
12-588: The SQL language. This makes them unavailable to stored procedures . QUEL has an extremely powerful aggregation capability. Aggregates can be nested, and different aggregates can have independent by-lists and/or restriction clauses. For example: This example illustrates one of the arguably less desirable quirks of QUEL, namely that all string comparisons are potentially pattern matches. y.str = "ii*" matches all y.str values starting with ii . In contrast, SQL uses = only for exact matches, while like
18-536: The first original Ingres papers: Here E is a tuple variable that ranges over the EMPLOYEE relation, and all tuples in that relation are found which satisfy the qualification `E.Name = "Jones"`. The result of the query is a new relation W, which has a single domain COMP that has been calculated for each qualifying tuple. Additional queries can then be made against the relation W. An equivalent SQL statement is: In this example,
24-482: The relation is being stored in a new table W. This is not a direct analog of the QUEL version; relations in QUEL are more similar to temporary tables seen in most modern SQL implementations. Here is a sample of a simple session that creates a table, inserts a row into it, and then retrieves and modifies the data inside it and finally deletes the row that was added (assuming that name is a unique field). Another feature of QUEL
30-604: The title Quel . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Quel&oldid=1084131773 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages QUEL query languages QUEL statements are always defined by tuple variables , which can be used to limit queries or return result sets. Consider this example, taken from one of
36-410: Was a built-in system for moving records en-masse into and out of the system. Consider this command: which creates a comma-delimited file of all the records in the student table. The d1 indicates a delimiter, as opposed to a data type. Changing the into to a from reverses the process. Similar commands are available in many SQL systems, but usually as external tools, as opposed to being internal to
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