Data Types
What types of data can be put into a web page database?
The first thing a webmaster must do to use a web page database is to define the database record structure and the index fields for searching. Most web page databases accept only a de-normalized data structure consisting of one record type. A delimited text file is the most common form of input. Each record in the database has the same number of fields. Think of the structure of a two dimensional spreadsheet where all the rows have the same columns. The data for the database can be prepared and maintained in any PC database program, spreadsheet, or text editor. The data supplied to the web page database must be prepared according to the vendor specifications.
Here is a sample of the data file that is provided to the Office Directory demo applet. It contains 4 or 5 fields per record each separated by commas. For this web page database the first field contains the database index as a string of 0's and 1's. This index saves storage in the HTML document. There is a byte in the index field for each checkbox on the screen. A 1 byte indicates this record has a checkbox and a 0 byte states it does not. The other four fields correspond to the city, country, telephone and email address for the record.
1100110,Adelaide SA,Australia,61-8-222-0000
1111111,Bellevue WA,United States,(206) 555-1212,blue.sky@rain.com
0100110,Belgique,Belguim,32-2-123-45-67
0111000,Birmingham AL,United States,205-999-9888,george@bham.com
1100110,Brisbane QLD,Australia,61-7-3838-3838
Web page databases support text data like; product name, description, price and availability date. Java uses the Unicode character encoding system, which currently contains approximately 34,000 distinct characters to support the majority of worldwide languages. However, Unicode support is limited to the available font set on the desktop computer.
Web page databases can be deployed as subsets of large databases maintained on the server. There is usually a convenient and logical way to segment portions of the main database into manageable sets for your visitors. Subsets may be created by time, geographical region, or alphabetically. So even though you have a big database on the server doesn't mean your users need to search it directly. You can perform a valuable service by segmenting and indexing the data for manipulation on the web page visitor's desktop.
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