Data Query Statement

A Data Query Statement is a program statement (expressed in a data querying language) that results in a report.

• Context:
  • It can be associated to a Query Plan.
  • It can be processed by a Query Optimizer.
  • It can be supported by a Database System, such as a database querying system.
  • It can range from being a Data Value Data Query to being an Analytical Data Query (such as an aggregation query).
  • It can range from being a Declarative Query to being an Imperative Query.
  • It can (often) be a Relational Data Query Statement.
  • ...
• Example(s):
  • a SQL SELECT Statement, such as a: HiveQL Query, MySQL Query.
  • a Datalog Query.
  • a XQuery Query.
  • a Graph Query.
  • ...
• Counter-Example(s)
  • a Data Structure Definition Statement.
  • a Data Manipulation Statement.
• See: SQL Query, Database Querying Task.

References

2017

• Jeffrey F. Naughton. (2017). "Broadening and deepening query optimization yet still making progress: technical perspective." In: ACM Communications.
  • QUOTE: Query optimization is a fundamental problem in data management. Simply put, most database query languages are declarative rather than imperative — that is, they specify properties the answer should satisfy, rather than give an algorithm to compute the answer. The best known and most widely used database query language — SQL — is a prime example of a language for which optimization is essential. By "essential," I mean that database optimization is not a matter of shaving 10% or even a factor of 2x from a query's execution time. In database query evaluation, the difference between a good plan and a bad or even average plan can be multiple orders of magnitude — so successful query optimization makes the difference between a plan that runs quickly and one that never finishes at all.

• Concept