Dynamic Queries are queries that are executed during run-time. In general, they are constructed dynamically with the help of desktop-resident query tools.
Many, if not, most of the database management systems require that the end user create and formulate complex queries in the presumption that these end users are very familiar with the underlying structure of the database. A query on a database is usually expressed using high level query language such as Structured Query Language (SQL).
In many cases, having end users do the complex query construction may work well but there are also less technically skilled users of database systems who may find using and understanding the database difficult and time consuming.
Given the last situation above, it is very clear that there needs to be a way so that non-technical people can use quick yet powerful query methods for retrieving data from the database.
Dynamic queries were originally conceived as a visualization technique for very large database implementations. But today’s dynamic queries are that and more. Dynamic queries can allow the user to specify certain selection criteria continuously and simultaneously in order to see how the data that satisfies the criteria changes. Dynamic Queries are not pre-processed.
Dynamic queries are represented by a number of widgets such as a slider. A slider may have a label with a field indicating current value, a slider bar with a drag box and value at each end of the slider to indicate the minimum and maximum values. When one drags the box using the mouse, the value in the slider changes. The interaction between the dynamic query mechanism and the database visualization interface is very important.
For example, there is a graphical map on a webpage displaying the locations of house for sale and all the data on the map (number of houses, specification of houses, are mapped into a database). The webpage contains a slider such that moving the slide to minimum or maximum also changes the selection criteria.
Dynamic queries can allow one to identify quickly which houses are the expensive kinds and which ones are not within the certain coverage area. Queries change with the movement of the slider, so this is the perfect example of dynamic query.
Dynamic queries make a great component for graphical database driven applications. The combination of a graphical front end and dynamic queries back end results in a more desirable database interface which represents the query graphically and provides a visible limit on the query range.
The same combination can also provide a graphical representation of the database with the query results while being able to give immediate feedback of the results after every adjustment of the query. Finally, with a graphical interface linked to dynamic queries, even very novice users or non-technical people can be allowed to work with little or no training on certain software applications that feature powerful functionalities.
Dynamic queries are as ubiquitous as the database implementation itself. Because of today’s data driven business environment, more and more data are coming in and out of corporate data warehouses. If in the past, the scenario was that only high ranking officials of the company need frequent access to updated data, today’s scenario is that every staff in the company needs to access data. In the human resource department alone, nobody is spared from needing data because even janitors need to access their daily time records and other related data. With dynamic queries, data access can be a lot easier.
In the internet, dynamic queries go hand in hand with dynamic webpages powered by back end programming languages. Today’s e-commerce websites employ dynamic queries. Perhaps the best example of dynamic queries with graphical interface deployed on the web is the Google Earth application.