Search results
Results From The WOW.Com Content Network
Database testing mainly deals with finding errors in the databases so as to eliminate them. This will improve the quality of the database or web-based system. Database testing should be distinguished from strategies to deal with other problems such as database crashes, broken insertions, deletions or updates.
In database theory, the query evaluation problem is the problem [verification needed] of determining the answers to a query on a database. Research in database theory aims at determining the computational complexity of answering different kinds of queries over databases, in particular over relational databases .
Broadly, query languages can be classified according to whether they are database query languages or information retrieval query languages. The difference is that a database query language attempts to give factual answers to factual questions, while an information retrieval query language attempts to find documents containing information that is relevant to an area of inquiry.
Software testing is the act of checking whether ... actions such as executing SQL statements against the database and then executing queries to ensure that the ...
Queries allow the user to describe desired data, leaving the database management system (DBMS) to carry out planning, optimizing, and performing the physical operations necessary to produce that result as it chooses. A query includes a list of columns to include in the final result, normally immediately following the SELECT keyword.
In information retrieval, a query does not uniquely identify a single object in the collection. Instead, several objects may match the query, perhaps with different degrees of relevance. An object is an entity that is represented by information in a content collection or database. User queries are matched against the database information.
The database translates the query into a "query plan" which may vary between executions, database versions and database software. This functionality is called the "query optimizer" as it is responsible for finding the best possible execution plan for the query, within applicable constraints. The SELECT statement has many optional clauses:
Data query language (DQL) is part of the base grouping of SQL sub-languages. These sub-languages are mainly categorized into four categories: a data query language (DQL), a data definition language (DDL), a data control language (DCL), and a data manipulation language (DML).