• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint

Query Languages

A query can be thought of as a request of the database, the response to which is a new table, which I will refer to as a result table . For instance, referring to the LIBRARY database, we might request the titles and prices of all books published by Big House that cost over $20.00. The result table in this case is shown in Table 5-1.

Table 5-1. Books published by Big House costing over $20.00

Title

Price

PubName

On Liberty

$25.00

Big House

Iliad

$25.00

Big House

Visual Basic

$25.00

Big House

C++

$29.95

Big House

It is probably not necessary to emphasize the importance of queries, for what good is a database if we have no way to extract the data in meaningful forms?


PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint