DBMS - Interview Questions and Answers

  1. What are the functions of a reporting system?
    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.
  2. What is OLAP?
    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.
  3. What is market basket analysis?
    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.

  4. Explain the differences between structured data and unstructured data.
    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.
  5. Explain why it is still necessary to have at least some familiarity with file processing systems even though it has become evident that traditional file processing systems have a number of shortcomings and limitations.
    Many businesses still use file processing systems today. This is especially true in the creation of backups for a database system. In addition, if you understand some of the limitations of a file processing system such as program-data dependence, duplication of data, limited data sharing, lengthy development times, and excessive program maintenance, you can try and avoid them as you design and develop a databases.
  6. What are some of the disadvantages associated with conventional file processing systems?
    There are five disadvantages. Program-data dependence occurs when file descriptions need to be changed in all programs whenever a file description changes. Duplication of data is storing the data more than one time. Limited data sharing occurs when the files are private so no one outside of one application can access the data. Lengthy development times exist because file processing systems takes longer to develop. Lastly, excessive program maintenance exists since the effort to maintain a program is larger in this environment.

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