Steps involved in converting a query into its equivalent internal form include generation of logically equivalent expressions, using equivalence rules, secondly providing enough information for extracting alternate solutions and finally optimizing the query. Queries written in high level languages are transformed into lower level forms by making use of relational algebra. Query is an ad-hoc reporting tool that allows you to retrieve data that is stored in the application. It gives users the ability to produce a report of information from a database. The word "Query" may be defined as retrieval of meaningful information. The language used to provide various manipulations like retrieval of information that is already available within the database, insertion of new information into the database, deletion of information from the database and modification of data stored in the database is referred to as "DML' (Data Manipulation Language). A subset of the DML that is used for writing a query is called a "Query Language". "Query Processing" is the method by which we can obtain the best plan, used in implementing the database request. In search, true success comes from understanding what the user is asking from their query.
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