Web Databases

There are many different database systems available for web hosting. The most common are MS Access, MySQL, SQL Server, and Oracle. When a web site requires a simple database solution, Microsoft Access is a very popular option.Access is not well suited for very high-traffic, and not as powerful as Oracle or SQL Server. SQL is the language for accessing databases. If you want your web site to be able to store and retrieve data from a database, your web server should have access to a database-system that uses the SQL language.

 

 

 

 

 

     

     

 

 

Microsoft's SQL Server is one of the most popular database software for database-driven web sites with high traffic. SQL Server is a very powerful, robust and full featured SQL database system. Oracle is also a very popular database software for database-driven web sites with high traffic and a full featured SQL database system. MySQL is a popular database server for lower traffic web sites.MySQL is an inexpensive alternative to the expensive Microsoft and Oracle solutions.  

What is ADO?

  • ADO is a Microsoft technology
  • ADO stands for ActiveX Data Objects
  • ADO is a Microsoft Active-X component
  • ADO is automatically installed with Microsoft IIS
  • ADO is a programming interface to access data in a database

Accessing a Database from an ASP Page

The common way to access a database from inside an ASP page is to:
  1. Create an ADO connection to a database
  2. Open the database connection
  3. Create an ADO recordset
  4. Open the recordset
  5. Extract the data you need from the recordset
  6. Close the recordset
  7. Close the connection

Create a DSN-less Database Connection

The easiest way to connect to a database is to use a DSN-less connection. A DSN-less connection can be used against any Microsoft Access database on your web site.

If you have a database called "northwind.mdb" located in a web directory like "c:/webdata/", you can connect to the database with the following ASP code:
  
<%
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open "c:/webdata/northwind.mdb"
%>

Note, from the example above, that you have to specify the Microsoft Access database driver (Provider) and the physical path to the database on your computer.

Create an ODBC Database Connection

If you have an ODBC database called "northwind" you can connect to the database with the following ASP code:
  
<%
set conn=Server.CreateObject("ADODB.Connection") 
conn.Open "northwind"
%>

With an ODBC connection, you can connect to any database, on any computer in your network, as long as an ODBC connection is available.

An ODBC Connection to a MS Access Database

Here is how to create a connection to a MS Access Database: 
  1. Open the ODBC icon in your Control Panel.
  2. Choose the System DSN tab.
  3. Click on Add in the System DSN tab.
  4. Select the Microsoft Access Driver. Click Finish.
  5. In the next screen, click Select to locate the database.
  6. Give the database a Data Source Name (DSN).
  7. Click OK.
Note that this configuration has to be done on the computer where your web site is located. If you are running Personal Web Server (PWS) or Internet Information Server (IIS) on your own computer, the instructions above will work, but if your web site is located on a remote server, you have to have physical access to that server, or ask your web host to do this for you. 

The ADO Connection Object

The ADO Connection object is used to create an open connection to a data source. Through this connection, you can access and manipulate a database.

Create an ADO Table Recordset

After an ADO Database Connection has been created, as demonstrated in the previous chapter, it is possible to create an ADO Recordset. 

Suppose we have a database named "Northwind", we can get access to the "Customers" table inside the database with the following lines:
  
<%
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open "c:/webdata/northwind.mdb"
set rs=Server.CreateObject("ADODB.recordset")
rs.Open "Customers", conn
%>

Create an ADO SQL Recordset

We can also get access to the data in the "Customers" table using SQL:
  
<%
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open "c:/webdata/northwind.mdb"
set rs=Server.CreateObject("ADODB.recordset")
rs.Open "Select * from Customers", conn
%>

Extract Data from the Recordset

After a recordset is opened, we can extract data from recordset. 

Suppose we have a database named "Northwind", we can get access to the "Customers" table inside the database with the following lines:
  
<%
set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open "c:/webdata/northwind.mdb"
set rs=Server.CreateObject("ADODB.recordset")
rs.Open "Select * from Customers", conn
for each x in rs.fields
   response.write(x.name)
   response.write(" = ")
   response.write(x.value)
next
%>

The ADO Recordset Object

The ADO Recordset object is used to hold a set of records from a database table. 

 

 

 

Email: Dr. Kirk P. Arnett, CCP, DBA