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{{Short description|Query language for object-oriented databases}}
{{inline|date=March 2025}}

'''Object Query Language''' ('''OQL''') is a [[query language]] standard for [[object database|object-oriented databases]] modeled after [[SQL]] and developed by the [[Object Data Management Group]] (ODMG). Because of its overall complexity the complete OQL standard has not yet been fully implemented in any software. The OQL standard influenced the design of later query languages such as [[JDOQL]] and [[EJB QL]], though none are considered to be any version of OQL.

==General rules==
The following rules apply to OQL statements:
* All complete statements must be terminated by a semi-colon.
* A list of entries in OQL is usually separated by commas but not terminated by a comma(,).
* Strings of text are enclosed by matching quotation marks.

==Examples==
===Simple query===
The following example illustrates how one might retrieve the [[CPU]]-speed of all PCs with more than 64MB of [[random-access memory|RAM]] from a fictional [[Personal computer|PC]] database:

<syntaxhighlight lang="sql">
SELECT pc.cpuspeed
FROM PCs pc
WHERE pc.ram > 64;
</syntaxhighlight>

===Query with grouping and aggregation===
The following example illustrates how one might retrieve the average amount of [[random-access memory|RAM]] on a [[Personal computer|PC]], grouped by manufacturer:

<syntaxhighlight lang="sql">
SELECT manufacturer, AVG(SELECT part.pc.ram FROM partition part)
FROM PCs pc
GROUP BY manufacturer: pc.manufacturer;
</syntaxhighlight>

Note the use of the keyword <code>partition</code>, as opposed to aggregation in traditional SQL.

==References==
{{refbegin}}

*{{cite book |last1=Dietrich |first1=Suzanne |last2=Urban |first2=Susan |title=Fundamentals of Object Databases |date=31 May 2022 |publisher=[[Springer Nature]] |isbn=978-3-031-01844-2 |pages=31–52 |chapter-url=https://books.google.com/books?id=JYdyEAAAQBAJ&dq=%22Object+Query+Language%22+-wikipedia&pg=PA31 |language=en |chapter=2.4 The ODMG Query Language}}

*{{cite book |last1=Cattell |first1=Roderic Geoffrey Galton |last2=Barry |first2=Douglas K. |last3=Berler |first3=Mark |title=The Object Data Standard: ODMG 3.0 |date=2000 |publisher=[[Morgan Kaufmann]] |isbn=978-1-55860-647-0 |pages=89–152 |url=https://books.google.com/books?id=2-FF-aQ_twQC |access-date=31 March 2025 |language=en |chapter=Object Query Language}}</ref>

{{refend}}

==See also==
* [[Object Data Management Group]] (ODMG)
* Object Definition Language

==References==
{{reflist}}

{{Query languages}}

[[Category:Query languages]]

{{Soft-eng-stub}}
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Object Query Language - Revision history

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