Transcript Creating Web Databases.

Part 1
Persistent Data
 Web applications remember your setting by means of a
database linked to the site
Central Sales Database
 A site such as Amazon has a central data store and users
may browse the content from different locations
To set this up we need two things…


A Database Management System
Some sort of data aware objects
Database Management Systems
 For a commercial web site the following are examples of
suitable Database Management Systems (DBMS)
 MySQL
 An “open source” (i.e. free) DBMS that runs on Windows, MAC and
UNIX platforms
 Oracle
 A company that makes powerful DBMS
 SQL Server
 Microsoft’s DBMS, a version of this comes “free” with Visual Studio
Microsoft Access
 Only ten users may access the database at a given time
(This limitation may be overcome by means of using a
different operating system e.g. Windows Server)
 not good for building your multimillion pound online
store
 However…
 Most students are familiar with the application
 It is part of the Microsoft Office
 It is easy to set up and use
Data Aware Objects
 Objects are used allow our programs to control computer
technology
 The email object
 allows us to create emails
 The SMTP client object
 allows us to control an SMTP server, i.e. send emails.
 The variable (object)
 allows us to store data in the RAM
 Control objects
 allow us to set up regions of the screen so the screen so the user may
interact with it.
ADO.NET (Active Data Objects)
 Used to control databases
 Problem!
 It is huge and complex and would need a year long
course just to get to grips with it
The DatabaseTable Object
 A custom object written for this module
 Allows simple control of a database
 Hides ADO.NET so you can get on with the task at
hand
 DatabaseTable acts as a kind of “secretary”. You
send it a simple command and then it uses
ADO.NET on your behalf to interact with the
database
Four Things we want to do

Produce a list of records for searching or so that
the user may see them all at once

Add a new record to the database

Edit an existing record in the database

Delete a record
Structured Query Language
 SQL allows us to manipulate data in the database
 SQL combined with concatenation provides us with a
powerful tool to control the data
Consider the Following Data
 The parameter MessageNo = 3
Add Validation