3 A Motivating Example

  Example 1 Suppose we want to search for title, price, supplier, and review of books about cancer, published in 1996, looking at the reviews and compare the prices before making a purchase decision. The parameters of interest to this query are the price, year, title, the supplier name, and the book reviews. We may ask query Q: get the title, price, the supplier, and the reviews of books about cancer that were published in 1996. We may enter the query using a SQL-like on-line form (e.g., The DIOM Interface Query Language: IQL [7]) as follows: