prose date October 2010 refimprove date October 2010 Query languages are computer language s used to make ... to whether they are database query languages or information retrieval querylanguage s. The difference is that a database querylanguage attempts to give factual answers to factual questions, while an information retrieval querylanguage attempts to find documents containing information that is relevant to an area of inquiry. Examples include .QL is a proprietary object oriented querylanguage for querying relational database s successor of Datalog Contextual QueryLanguage CQL a formal ... catalogues. CQLF CODASYL QueryLanguage, Flat is a querylanguage for CODASYL type databases Concept Oriented QueryLanguage COQL is used in the concept oriented model COM . It is based on a novel ... dimensional analysis, analytical operations and inference D data language specification D is a query ... Data Mining Extensions DMX is a querylanguage for Data Mining models Datalog is a querylanguage ... language that translates HTTP queries to SQL ISBL is a querylanguage for PRTV , one of the earliest ... directory services running over TCP IP Molecular QueryLanguage MQL is a cheminformatics query ... eXpressions MDX is a querylanguage for OLAP databases Object QueryLanguage OQL is Object QueryLanguage Object Constraint Language OCL Object Constraint Language . Despite its name, OCL is also an object querylanguage and an Object Management Group OMG standard OPath , intended for use in querying WinFS Stores Poliqarp QueryLanguage is a special querylanguage designed to analyze ... access language, similar in most ways to SQL RDQL is a Resource Description Framework RDF querylanguage ... search SPARQL is a querylanguage for Resource Description Framework RDF Graph mathematics graphs SQL is a well known querylanguage and Data Manipulation Language for relational database s SuprTool is a proprietary querylanguage for SuprTool, a database access program used for accessing data in Image ... more details
An information retrieval querylanguage is a querylanguage used to make queries into database, where the semantics of the query are defined not by a precise rendering of a formal syntax, but by an interpretation of the most suitable results of the query. Of importance in IR query languages is weighting and ranking, relevance orientation , semantic relativism and logic based probabilism. An example of an IR querylanguage is Contextual QueryLanguage CQL , a formal language for representing queries to Information Retrieval systems such as web indexes, bibliographic catalogs and museum collection information. See also Controlled vocabulary Free text searching Information retrieval SQL Document retrieval Text retrieval Database querylanguage External links http zing.z3950.org cql CQL Common QueryLanguage Database Category Query languages compu lang stub de Abfragesprache ... more details
Object QueryLanguage OQL is a querylanguage standard for object database object oriented databases modeled after SQL . OQL was developed by the Object Data Management Group ODMG . Because of its overall complexity no vendor has ever fully implemented the complete OQL. OQL has influenced the design of some of the newer query languages like JDOQL and EJB QL , but they can t be considered as different flavors of OQL. General Rules of OQL 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 code SELECT pc.cpuspeed br FROM PCs pc br WHERE pc.ram 64 br code Query with grouping and aggregation The following example illustrates how one might retrieve the average amount of RAM on a Personal computer PC , grouped by manufacturer code SELECT manufacturer, AVG SELECT part.pc.ram FROM partition part br FROM PCs pc br GROUP BY manufacturer pc.manufacturer code Note the use of the keyword code partition code , as opposed to aggregation in traditional SQL . References reflist See also ODMG Object Data Management Group Object Definition LanguageQuery languages Soft eng stub Compu lang stub Category Computer languages Category Query languages de Object QueryLanguage es Object QueryLanguage eu Object QueryLanguage fr Object QueryLanguage it Object QueryLanguage ja pl Object QueryLanguage ... more details
Chess QueryLanguage CQL is a structured querylanguage which is designed to allow chess players and researchers to search for games, positions, problems, and studies in a quick and relatively easy manner. The user specifies the items that they are looking for, and the database in which to search. After running, the query creates a file in Portable Game Notation PGN format that contains all the games or positions matching the query criteria. The language is designed to be extremely flexible for example, a user does not have to define exactly the position or theme that they are looking for, but can modify the query so that it will find similar results within certain parameters. ref http www.xs4all.nl timkr chess2 cql.htm Chess QueryLanguage example Tim Krabbé s Chess Site Retrieved on 2007 07 04 ref Items and themes that CQL can search for include, but are not limited to ref http products.convekta.com 860 2 searches.htm CQL criteria convecta.com Retrieved on 2007 07 04 ref Player names Date and location of games Chess opening used Certain moves or Combination chess combinations of moves Certain pieces located on certain squares Patterns of pieces in certain locations Which pieces each side has left Complex criteria such as King chess king safety or certain pawn structure s. References references External links http www.rbnn.com cql CQL manual and download page http www.chessassistance.com News ChessAssistant8 Review.html A review of a chess analysis engine with CQL support Category Computer chess Category Query languages de Chess QueryLanguage fr Chess QueryLanguage ... more details
An RDF querylanguage is a computer language , specifically a querylanguage for database s, able to retrieve and manipulate data stored in Resource Description Framework format. SPARQL is emerging as the de facto RDF querylanguage, and is a W3C Recommendation . ref cite web url http www.w3.org TR rdf sparql query title SPARQL QueryLanguage for RDF last1 Prud hommeaux first1 Eric last2 Seaborne first2 Andy date 15 January 2008 work W3C publisher World Wide Web Consortium ref Released as a Candidate Recommendation in April 2006, it returned to Working Draft status in October 2006, due to open issues. It returned to Candidate Recommendation status in June 2007. ref cite web url http www.w3.org blog SW 2007 06 15 sparql is a candidate recommendation title SPARQL is a Candidate Recommendation ... web url http www.w3.org News 2007 item247 title Three SPARQL Proposed Recommendations SPARQL QueryLanguage for RDF Query Results XML Format Protocol for RDF date 13 November 2007 work W3C News in 2007 ... like SeRQL , SQL like, similar to RQL RVL Versa querylanguage , compact syntax non SQL like , solely implemented in 4Suite Python programming language Python XUL has a http developer.mozilla.org en docs ... Consortium ref Other RDF query languages DQL , XML based, queries and results expressed in DAML OIL .... XUL uses RDF extensively for databinding. Adenine programming language Adenine programming language written in RDF . External links http www.w3.org TandS QL QL98 pp rdfquery.html RDF Query specification http www.w3.org 2001 11 13 RDF Query Rules RDF querylanguage survey http web.archive.org web 20080702143156 http www.aifb.uni karlsruhe.de WBS pha rdf query A Comparison of some RDF Query Languages http rdfstore.sourceforge.net 2002 06 24 rdf query RDF query use cases, including querylanguage samples http www.w3.org TR rdf sparql query SparQL References Reflist Category RDF data access Category Resource Description Framework Query languages Category Query languages ja RDF pl RDQL ... more details
POV date April 2011 Facebook QueryLanguage FQL is a querylanguage that allows querying Facebook user data by using a SQL style interface and without using the Application programming interface API . ref cite web url http developers.facebook.com docs reference fql title Facebook QueryLanguage FQL work Documentation publisher Facebook accessdate 2010 12 16 ref The beauty in FQL is the ability to query any Facebook data just like from an SQL database. In the following query, we pull four different types of data from a single table status where the user is me. When trying to do this yourself, you need to log into Facebook from your application and you also probably need to grant access to whatever data you want to pull. Due to the growing number of privacy concerns for social networks, most people have disabled most data to be shown to anyone thus your application will not be able to see it. However, once you login and grant access, you can see all data that you grant access to. source lang sql SELECT status id,message,time,source FROM status WHERE uid me source Once data is returned from an FQL query, it is found in JSON format by default. With JSON, it can be broken down and manipulated on a web page. References reflist Facebook navbox Category Facebook Category Query languages id Facebook QueryLanguage web software stub ... more details
The Molecular QueryLanguage MQL was designed to allow more complex, problem specific search methods in chemoinformatics . In contrast to the widely used Smiles arbitrary target specification SMARTS queries, MQL provides for the specification of spatial and physicochemical properties of atoms and bonds. Additionally, it can easily be extended to handle non atom based graphs, also known as reduced feature graphs. The querylanguage is based on an extended Backus Naur form EBNF using JavaCC . See also Smiles arbitrary target specification SMARTS International Chemical Identifier References E. Proschak, J. K. Wegner, A. Schü ller, G. Schneider, U. Fechner, Molecular QueryLanguage MQL A Context Free Grammar for Substructure Matching , J. Chem. Inf. Model., 2007 , 47 , 295 301. doi 10.1021 ci600305h External links http gecco.org.chemie.uni frankfurt.de mql Java Webstart application for MQL Query languages Category Cheminformatics ... more details
noref date June 2010 Infobox programming language name Java Persistence QueryLanguage logo paradigm year designer developer latest release version latest release date latest test version latest test date turing complete No typing implementations dialects influenced by SQL influenced operating system Cross platform license website The Java Persistence QueryLanguage JPQL is a platform independent object oriented querylanguage defined as part of the Java Persistence API specification. JPQL is used to make queries against entities stored in a relational database. It is heavily inspired by SQL , and its queries resemble SQL queries in syntax, but operate against JPA entity objects rather than directly with database tables. In addition to retrieving objects code SELECT code queries , JPQL supports set based code UPDATE code and code DELETE code queries. Examples Suppose we have JPA entity classes defined like this getter and setter methods omitted for simplicity source lang java Entity public class Author Id private Integer id private String firstName private String lastName ManyToMany private ... source Hibernate QueryLanguage JPQL is based on the Hibernate Java Hibernate QueryLanguage HQL Hibernate QueryLanguage HQL , an earlier non standard querylanguage included in the Hibernate ... Full QueryLanguage Syntax from The Java EE 5 Tutorial http www.objectdb.com java jpa query JPA Queries and JPQL a chapter of the ObjectDB Manual http torpedoquery.org Type safe Hibernate HQL query engine TorpedoQuery Java Persistence API Category Query languages Category Data modeling languages Category Java enterprise platform cs JPQL fr Java Persistence QueryLanguage hu Java Persistence QueryLanguage ... publisher private List Book books source Then a simple query to retrieve the list of all authors, ordered ... a FROM Author a WHERE lastName IS NULL OR LOWER a.lastName lastName Queryquery getEntityManager .createQuery ... more details
Multiple issues unreferenced June 2010 orphan February 2010 notability October 2011 distinguish Microsoft Access Access , the successor to ENGLISH programming language ENGLISH , is an English language English like query language used in the Pick operating system . The original name ENGLISH is something of a misnomer, as PICK s flexible dictionary structure meant that file and attribute names could be given aliases in any natural language. For instance the command SORT could be given the alias TRIEZ, the file CUSTOMER the alias CLIENT, the attribute BALANCE the alias BILAN and the particle BY the alias PAR. This would allow the database to be interrogated using the French language command string TRIEZ CLIENT PAR BILAN , resulting in a list of customers by balance. FOLDOC Category Query languages prog lang stub ... more details
Contextual QueryLanguage CQL , previously known as Common QueryLanguage , ref http www.loc.gov standards sru specs cql.html CQL the Contextual QueryLanguage Specifications SRU Search Retrieval via URL, Standards, Library of Congress ref is a formal language for representing queries to information retrieval systems such as search engine s, bibliography bibliographic catalogs and museum collection information. Based on the semantics of Z39.50 , its design objective is that queries be human readable and writable, and that the language be intuitive while maintaining the expressiveness of more complex querylanguage s. It is being developed and maintained by the Z39.50 Maintenance Agency, part of the Library of Congress . Examples of query syntax Simple queries blockquote tt dinosaur br complete dinosaur br title complete dinosaur br title exact the complete dinosaur tt blockquote Queries using Boolean logic blockquote tt dinosaur or bird br Palomar assignment and ice age br dinosaur not reptile br dinosaur and bird or dinobird br bird or dinosaur and feathers or scales br feathered dinosaur and yixian or jehol tt blockquote Queries accessing index publishing publication indexes blockquote tt publicationYear 1980 br lengthOfFemur 2.4 br bioMass 100 tt blockquote Queries based on the proximity of words to each other in a document blockquote tt ribs prox distance 5 chevrons br ribs prox unit sentence chevrons br ribs prox distance 0 unit paragraph chevrons tt blockquote Queries across multiple Dimension data warehouse dimensions blockquote tt date within 2002 2005 br dateRange encloses 2003 tt blockquote Queries based on Relevance information retrieval relevance blockquote tt ... of Congress Category Query languages Category Knowledge representation languages de Common QueryLanguage it Common QueryLanguage uk Common QueryLanguage ... zing.z3950.org cql intro.html A Gentle Introduction to CQL Query languages USGovernment sourceURL ... more details
About querylanguage vehicle Nissan Versa Versa is an RDF querylanguage , that is, a querylanguage for database s, able to retrieve and manipulate data stored in Resource Description Framework RDF format. Versa differs from most other RDF query languages, which are typically based on SQL or specialized XML vocabularies. Although the design of Versa was inspired by XPath , its compact, functional programming functional syntax also somewhat resembles Lisp programming language Lisp . As of 2006 , the only Versa implementation is in the Python programming language Python language, open source 4Suite XML framework. History and status Versa s origins can be traced to 2000, when professional XML consultancy Fourthought, Inc. began developing RIL, an open, XML based RDF Inference Language . RIL was implemented briefly in Fourthought s 4Suite Server product, which allowed for persistent storage and querying of an RDF model and associated XML document store. In October 2001, the query portion of RIL was spun off into a separate project named Versa, with the intent that after Versa stabilized, development would resume to establish RIL as a formal language for working Versa query results. RIL development never resumed, however inference abilities in 4Suite were easily handled by XSLT extensions and did not need a separate language. Versa initially had limits that required the language to be redesigned ... lpt a 2005 07 20 versa.html XML.com Versa Path Based RDF QueryLanguage irc irc.freenode.net ..., experimentation, and debugging http rdfstore.sourceforge.net 2002 06 24 rdf query RDF query use cases, including querylanguage samples Category Semantic Web Category Query languages Category RDF ... Get the URIs of all code edu Subject code s having a code rdfs label code matching code Russian language code type edu Subject rdfs label eq Russian language Get the URIs of all super code edu Subject ... wiki Russian language nowiki code traverse nowiki http en.wikipedia.org wiki Russian language nowiki ... more details
Yahoo querylanguage YQL is an SQL like querylanguage created by Yahoo as part of their Yahoo Developer Network Developer Network . YQL is designed to retrieve and manipulate data from API s through a single Web interface, thus allowing mashup digital mashups that enable developers to create their own applications. ref cite news url http www.pcworld.com businesscenter article 164067 yahoo extends yql web data query platform.html work PC World magazine PC World title Yahoo Extends YQL Web Data Query Platform date April 29, 2009 last Perez first Juan Carlos ref Initially launched in October 2008 with access to Yahoo APIs, ref cite news url http www.eweek.com c a Application Development Yahoo Launches YQL Execute Updates YSlow 660481 work eWeek title Yahoo Launches YQL Execute, Updates YSlow last Kolakowski first Nicholas date April 29, 2009 ref February 2009 saw the addition of open data table s from third parties such as Google Reader , the Guardian newspaper Guardian , and The New York Times . ref name rww Some of these APIs still require an API key to access them. On April 29th of 2009, Yahoo introduced the capability to execute the tables of data built through YQL using JavaScript run on the company s servers for free. ref name rww cite news url http www.readwriteweb.com archives theres a great amount of.php work ReadWriteWeb last O Dell first Jolie date May 2, 2009 title Developers Never Mind the APIs, Here s YQL Execute ref References Reflist External links http developer.yahoo.com yql Official site , including the YQL console See also WSO2 Mashup Server Yahoo Pipes Yahoo Inc. Query languages www stub Category Yahoo Development querylanguage Category Query languages ... more details
The Knowledge Query and Manipulation Language , or KQML , is a language and protocol for communication among software agents and knowledge based systems. It was developed in the early 1990s part of the DARPA knowledge Sharing Effort , which was aimed at developing techniques for building large scale knowledge bases which are shareable and reusable. While originally conceived of as an interface to knowledge based systems, it was soon repurposed as an Agent communication language . Work on KQML was led by Tim Finin of the University of Maryland, Baltimore County and Jay Weber of EITech and involved contributions from many researchers. The KQML message format and protocol can be used to interact with an intelligent system, either by an application program , or by another intelligent system. KQML s performatives are operations that agents perform on each other s knowledge and goal stores. Higher level interactions such as contract nets and negotiation are built using these. KQML s communication facilitators coordinate the interactions of other Multi agent system agents to support knowledge sharing. Experimental prototype systems support concurrent engineering, intelligent design, intelligent planning, and scheduling. KQML is superseded by FIPA ACL . See also Agent Communications Language Knowledge Interchange Format FIPA References FOLDOC External links http www.cs.umbc.edu kqml UMBC Agent Web Tim Finin Jay Weber Gio Wiederhold Michael Gensereth Richard Fritzzon Donald McKay James McGuire Richard Pelavin Stuart Shapiro Chris Beck http www.cs.umbc.edu KQML kqmlspec.ps DRAFT Specification of the KQML Agent Communication Language PostScript , June 15, 1993. Category Knowledge representation languages Category Multi agent systems de Knowledge Query and Manipulation Language fr Knowledge Query and Manipulation Language it KQML pt Knowledge Query and Manipulation Language ... more details
Orphan date February 2009 The Structured QueryLanguage Interface SQLI is the internal interface between an application and the Informix INFORMIX Online Dynamic Server . Starting from v10.0 Informix Dynamic Server also supports DRDA . External links http www 1.ibm.com support docview.wss?rs 630&context SSGU8G&dc DB520&uid swg21104625&loc en US&cs UTF 8&lang en&rss ct630db2 Setting SQLIDEBUG on the client side database software stub Category Application programming interfaces Category SQL data access ... more details
wiktionary query In general, a query is a form of question ing, in a line of inquiry. A query may also refer to The Queries , a set of 31 questions outlined by Isaac Newton beginning in 1704 Query Quaker , a question used for reflection and spiritual exercises among members of the Society of Friends Query complexity , a mapping from structures of one vocabulary to structures of another vocabulary In computing A precise request for information retrieval with database and information systems Querylanguage , a computer language used to make queries into databases and information systems Query string , in the World Wide Web, is an optional part of a Uniform Resource Locator URL that follows the first question mark ? Web search query , a query entered by users into web search engines Command query separation CQS , a concept in object oriented programming, especially in the Eiffel programming language jQuery , a lightweight JavaScript library that emphasizes interaction between JavaScript and HTML Persons with the surname Query Jeff Query , an American American Football football player Nate Query , a musician Russell Query, Web Developer See also Queue disambiguation Disambiguation de Query it Query nl Query ja pl Zapytanie bazy danych ru sr th ... more details
In descriptive complexity , a query is a mapping from structures of one signature logic signature to structures of another vocabulary. Neil Immerman , in his book Descriptive Complexity , use s the concept of query as the fundamental paradigm of computation p. 17 . Given signatures math sigma math and math tau math , we define the set of structure mathematical logic structure s on each language, math mbox STRUC sigma math and math mbox STRUC tau math . A query is then any mapping blockquote math I mbox STRUC sigma to mbox STRUC tau math blockquote Computational complexity theory can then be phrased in terms of the power of the mathematical logic necessary to express a given query. Order independent queries A query is order independent if the ordering of objects in the structure does not affect the results of the query. In databases, these queries correspond to generic query generic queries Immerman 1999, p. 18 . This isn t a great reference for this information, since it s in the background section. A reference that goes into more detail would be great. A query is order independent iff math I mathfrak A equiv I mathfrak B math for any isomorphic structures math mathfrak A math and math mathfrak B math . References cite book last Immerman first Neil authorlink Neil Immerman title Descriptive Complexity year 1999 publisher Springer Verlag location New York isbn 0 387 98600 6 comp sci theory stub Category Descriptive complexity ... more details
Query expansion QE is the process of reformulating a seed query to improve retrieval performance in information ... 2006 title A study of the effect of term proximity on query expansion journal Journal of Information ... search engine s, query expansion involves evaluating a user s input what words were typed into the search query area, and sometimes other types of data and expanding the search query to match additional documents. Query expansion involves techniques such as Finding synonym s of words, and searching ... by stemming each word in the search query Fixing Typographic error spelling errors and automatically ... queryQuery expansion is a methodology studied in the field of computer science , particularly within the realm of natural language processing and information retrieval . Precision and recall tradeoffs Search engines invoke query expansion to increase the quality of user search results. It is assumed ... information retrieval precision . By expanding a search query to search for the synonyms ... more results to comb through, regardless of the precision. The goal of query expansion in this regard ... to be more relevant to the user s desired query, are included, and without query expansion would ... of the defining problems in query expansion, regarding whether it is worthwhile to perform given the questionable ... this is implicitly handled by the query expansion algorithm, this explicitly affects the results ... language processing Stemming Morphology linguistics Software libraries http lucene qe.sourceforge.net ... query expansion with the use of Apache Lucene . http grasia.fdi.ucm.es jose query expansion LuceneQE State of Art query expansion for Lucene References D. Abberley, D. Kirby, S. Renals, and T. Robinson ... pubs 1999 esca99 thisl node6.html Query Expansion Concise, mathematical overview. R. Navigli, P. Velardi. http www.dcs.shef.ac.uk fabio ATEM03 navigli ecml03 atem.pdf An Analysis of Ontology based Query ... 26th, 2003, pp. 42 49 An analysis of query expansion methods relying on WordNet as the reference ... more details
unsourced date December 2007 In Computer Science , Query Throughput QthD is a measurement used to determine the performance of a database system . The throughput metric is a classical throughput measure characterizing the ability of the system to support a multi user workload in a balanced way. Background A number of querylanguagequery users S is chosen, each of which execute the full set of 17 queries in a different order Fact date February 2007 . In the background there is an update stream that runs a series of insert delete operations one pair for each query user . The choice of the number of users is at the discretion of the test sponsor. The throughput metric is computed as the total amount of work S× 17 , converted to hours from seconds 3600 seconds per hour , scaled by the database volume SF and divided by the total elapsed time T sub s sub required between the first query starting and the last query or update function completing. Therefore the complete formulation is math mathit QthD frac S times 17 times 3600 T s times mathit SF math Note that if the test sponsor chooses S 1 for the throughput test, for ease of benchmarking it is permissible to omit the throughput test and compute the throughput metric using timings obtained during the power test. Similarly, it is permissible to schedule the insert delete activity for the throughput test after all the queries complete. Fact date February 2007 See also See Transaction Processing Performance Council TPC . database stub Category Computer performance ... more details
Query by Example QBE is a database querylanguage for relational database s. It was devised by Mosh M. Zloof at IBM Research during the mid 1970s, in parallel to the development of SQL . It is the first graphical querylanguage, using visual tables where the user would enter commands, example elements and conditions. Many graphical front ends for databases use the ideas from QBE today. Originally limited only for the purpose of retrieving data, QBE was later extended to allow other operations, such as inserts, deletes and updates, as well as creation of temporary tables. The motivation behind QBE is that a parser can convert the user s actions into statements expressed in a database manipulation language, such as SQL . Behind the scenes, it is this statement that is actually executed. A suitably comprehensive front end can minimize the burden on the user to remember the finer details of SQL, and it is easier and more productive for end users and even programmers to select tables and columns by selecting them rather than typing in their names, In the context of information retrieval , QBE has a somewhat different meaning. The user can submit a document, or several documents, and ask ... a querylanguage such as SQL . The software can automatically generate the queries for the user usually ... relational database front ends, notably Microsoft Access, which implements Visual Query by Example ... , Starts With , Greater Than , and so forth. See also Microsoft Query by Example References references M. Zloof. Query by Example . AFIPS, 44, 1975. Raghu Ramakrishnan , Johannes Gehrke . Database ... dbbook openAccess thirdEdition qbe.pdf External links http pgfoundry.org projects qbe Query ... querycriteria examples Query by Example in Java using Hibernate Category Relational model Category Query languages compu lang stub ca Consulta mitjan ant exemple de Query by Example es B squeda mediante ejemplo fr Query By Example ja pl Query By Example pt Query by Example ru QBE ... more details
In the World Wide Web , a query string is the part of a Uniform Resource Locator URL that contains data ... The Mozilla URL location bar showing a URL with the query string code title Main page&action raw code ... its output as the required page. The query string is a part of the URL which is passed to the program ... which generates the web page. Structure A typical URL containing a query string is as follows code nowiki http server path program?query string nowiki code When a server receives a request for such a page, it runs a program if configured to do so , passing the code query string code unchanged to the program. The question mark is used as a separator and is not part of the query string. ref cite web ... year 2005 at Query section 3.4 separator , ref A link in a web page may have a URL that contains a query string. However, the main use of query strings is to contain the content of an HTML form web ... is encoded as a query string as follows code field sub 1 sub value sub 1 sub &field sub 2 sub value sub 2 sub &field sub 3 sub value sub 3 sub ... code The query string is composed of a series of field ... sub 3 sub ... code For each Field computer science field of the form, the query string contains a pair ... in the query string when the form is submitted This convention is a W3C recommendation. ref http ... html401 19991224 appendix notes.html h B.2.2 ref Technically, the form content is only encoded as a query ... as a query string, that is, is not added to the action URL of the form. Rather, the string is sent ... is used to separate a name from a value. A query string may need to be converted to satisfy these constraints ... URL encoding . In particular, encoding the query string uses the following rules Letters A Z ... ? code character. RFC 3986 specifies that the query component of a Uniform Resource Identifier URI ... query string is of common usage for referring to this part for the case of HTTP URLs. Example If a Form ... fields and presses the submit button, the program code test.cgi code will receive the following query ... more details
A query plan or query execution plan is an ordered set of steps used to access or modify information ... number of alternative ways to execute a given query, with widely varying performance. When a Information retrieval query is submitted to the database, the query optimizer evaluates some of the different, correct possible plans for executing the query and returns what it considers the best alternative. Because query optimizers are imperfect, database users and administrators sometimes need to manually examine and tune the plans produced by the optimizer to get better performance. Generating query ... query. Some packages feature tools which will generate a graphical representation of a query ... description of the query plan. Another mechanism for retrieving the query plan involves querying a virtual database table after executing the query to be examined. In Oracle, for instance, this can ... exploration of various attributes of the operators involved in the query plan, including the operator ... query plan. Textual plans The textual plan given for the same query in the screenshot is shown ... as e . ContactID ORDERED FORWARD pre It indicates that the query engine will do a scan over .... In order to tune the query, the user must understand the different operators that the database may use, and which ones might be more efficient than others while still providing semantically correct query results. Database tuning main Database tuning Reviewing the query plan can present opportunities ... is not properly taking advantage of existing indexes see query optimizer . Query tuning main Query optimizer The query optimizer will not always choose the best query plan for a given query. In some databases the query plan can be reviewed, problems found, and then the query optimizer given Hint SQL hints on how to improve it. In other databases alternatives to express the same query other queries that return the same results can be tried. Some query tools can generate embedded hints in the query ... more details
Unreferenced date December 2009 A query letter is a formal letter sent to magazine editors, literary agents and sometimes publishing publishing houses or companies. Writers write query letters to propose writing ideas. For example, a standard requested format for a manuscript query letter to a literary agent could be approximately 200 400 words, expressing the following information The topic of the work A short description of the plot A short bio of the author The target audience The literary agent would then decide whether to contact the author and request to see the manuscript, based on the contents of the query letter. In this sense, the query letter is an author s first step towards getting his her manuscript published. See also Literary agent Literary Agent Publishing DEFAULTSORT Query Letter Category Book publishing Literature stub ... more details
The query optimizer is the component of a database management system that attempts to determine the most efficient way to execute a Information retrieval query . The optimizer considers the possible query plan s for a given input query, and attempts to determine which of those plans will be the most efficient. Cost based query optimizers assign an estimated cost to each possible query plan, and choose the plan with the smallest cost. Costs are used to estimate the runtime cost of evaluating the query ... from the data dictionary . The set of query plans examined is formed by examining the possible ... query. Generally, the query optimizer cannot be accessed directly by users once queries are submitted to database server, and parsed by the parser, they are then passed to the query optimizer where optimization occurs. However, some database engines allow guiding the query optimizer with hint SQL hint s. Implementation Most query optimizers represent query plans as a Tree data structure tree of plan nodes . A plan node encapsulates a single operation that is required to execute the query. The nodes ... scan. Join ordering The performance of a query plan is determined largely by the order in which ..., and 1,000,000 rows, respectively, a query plan that joins B and C first can take several orders of magnitude more time to execute than one that joins A and C first. Most query optimizers determine Join ... ways to access each Relational model relation in the query are computed. Every relation in the query ... to answer a Predicate computer programming predicate in the query, an index scan can also be used .... Then all three relation query plans are computed, by joining each two relation plan produced by the previous phase with the remaining relations in the query. In this manner, a query plan is eventually ... order of the result set produced by a query plan, also called an interesting order . During dynamic programming, one query plan is considered to beat another query plan that produces the same result ... more details
Unreferenced date May 2008 A range query is a common database operation that retrieves all records where some value is between an upper and lower boundary. For example, list all employees with 3 to 5 years experience. Range queries are unusual because it is not generally known in advance how many entries a range query will return, or if it will return any at all. Many other queries, such as the top ten most senior employees, or the newest employee, can be done more efficiently because there is an upper bound to the number of results they will return. A query that returns exactly one result is sometimes called a Singleton mathematics singleton . Partial match query Match at least one of the requested keys Data structures for range query Range tree K D tree Category databases Database stub de Bereichsabfrage ... more details
Query optimization is a function of many relational database management system s in which multiple query plan s for satisfying a query are examined and a good query plan is identified. This may or not be the absolute best strategy because there are many ways of doing plans. There is a trade off between the amount of time spent figuring out the best plan and the amount running the plan. Different qualities of database management systems have different ways of balancing these two. Cost based query optimizer s evaluate the resource footprint of various query plans and use this as the basis for plan selection. Typically the resources which are costed are CPU path length, amount of disk buffer space, disk storage service time, and interconnect usage between units of parallelism. The set of query plans examined is formed by examining possible access paths e.g., primary index access, secondary index access, full file scan and various relational table join techniques e.g., merge join, hash join, product join . The search space can become quite large depending on the complexity of the SQL query. There are two types of optimization. These consist of logical optimization which generates a sequence of relational algebra to solve the query. In addition there is physical optimization which is used to determine the means of carrying out each operation. External links http www.sql performance tuning.com oracle sql performance tuning Information about query optimization http www.sql performance tuning.com oracle tuning tools Query optimization example Databases Category Database algorithms Category Database management systems Category SQL he ru ... more details
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