Interview Questions - DBMS

A reporting system has three functions: 1. Report authoring -- connecting to data sources, creating the report structure and formatting the report. 2. Report management -- defining who receives which reports, when they receive them and how the reports are delivered. 3. Report delivery -- based on report management metadata, either pushing the reports to the recipients or allowing them to be pulled by the recipients.

OnLine Analytical Processing (OLAP) is a Business Intelligence (BI) reporting system. OLAP provides the user with the capability to sum, count, average and do other simple arithmetic operations on groups of data. An OLAP report has measures and dimensions. Measures are the data values to be displayed. Dimensions are characteristics of the measures. OLAP reports are called OLAP cubes, although such reports are not limited to three dimensions.

Market basket analysis is a data mining technique that determines which sets of products tend to be purchased together. A common technique uses conditional probabilities. In addition to the basic probability that an item will be purchased, three results are of particular interest:

Support -- the probability of two items being purchased together.

Confidence -- the probability of a second item being purchased GIVEN that another item has been purchased.

Lift -- calculated as confidence divided by a basic probability, this shows the likelihood of a second item being purchased IF an item is purchased.

Structured data are facts concerning objects and events. The most important structured data are numeric, character, and dates. Structured data are stored in tabular form. Unstructured data are multimedia data such as documents, photographs, maps, images, sound, and video clips. Unstructured data are most commonly found on Web servers and Web-enabled databases.