query


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Related to query: Database query

query

[′kwir·ē]
(computer science)
A computer instruction to interrogate a data base.

query

(database, information science)
A user's (or agent's) request for information, generally as a formal request to a database or search engine.

SQL is the most common database query language.

query

(character)

query

To search for data. In addition to obtaining lists of records that match the search criteria, queries to a database allow for counting items and summing amounts. A query to a search engine such as Google or Bing yields a summary of the contents of Web pages and is more often called a "search."

For years, query and report programs have been the primary applications that produce output from information systems. A query implies an online request as required (look up that record), while a report implies a more elaborate printout with page headings and numbers that is typically produced at regular intervals such as end of month. See report writer.

Simple or Complex
Defining a query for a relational database can be extremely simple or very complex. If the query is based on one matching condition, such as "retrieve all customers who owe us more than $10,000," it is usually easy to define in a query language or program. However, "retrieve all customers who owe us more than $10,000 from purchasing toasters" is not easy. It requires several steps to determine how many toaster orders are in the balance due.

Tables Must Be Joined
Relational databases are designed to eliminate redundancy. The goal is to store a data item in one table and not have it duplicated in others. For example, an order record will contain the product number ordered, but often not its description. The description is stored in a product table. Thus, any printout of products ordered and their descriptions requires that the order table be linked to the product table for that query or report. Linking customer, order and product tables is a common example of "joining" tables to satisfy a query.

Contents of a Query
Most queries require at least the following conditions to be stated. First, which table or tables is the data coming from. If from two or more tables, what is the link between (typically account number or name). Next, define the selection criteria, which is the matching condition or filter. Lastly, define which fields in the tables are to be displayed or printed in the result. See SQL.


The Query Statement
This diagram depicts the typical conditions that have to be stated when querying a relational database.
References in periodicals archive ?
Create a query using the Copy of Direct Materials Budget table and Duplicate Items query as the data sources.
Query processing in big data is often expensive and requires special techniques completely different from traditional database.
1 or higher to use query cache and then to see if query cache is enabled (http://www.
Query reformulation is an interactive process of query modification to help users meet their information needs.
Both the classification scheme and the fuzzy-related thesaurus based query refinement are based on an unsupervised neural network, the Self-Organising Map (SOM) [6].
Select the information you want in the Query Wizard--Choose Columns dialog box by scrolling down the Available To help readers follow the instructions in this article, we use two different typefaces: Boldface type is used to identify the names of icons, agendas and URLs.
However, a sizable percentage of users did go on to either modify their original query or view subsequent results.
Excite does have one drawback: You can conduct an advanced search only after you've initiated a primary query.
FIST has a powerful interactive query capability allowing access to all aspects of FIST extracted by any combination of fields and sequence locally printable and downloadable in most formats.
Quick Query provides users with a wide range of information.
Currently, the response time is within four weeks for a multiple person query and within one week for an individual query.
For example, a "chocolate" query at hakia delivers a "Gallery", search results that are displayed in a categorized view by meaning-based aspects of "chocolate".