ADO

ADO is a Microsoft technology, and stands for ActiveX Data Objects.

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

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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

ADO Database Connection

Before a database can be accessed from a web page, a database connection has to be established.

An ODBC Connection to an 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.

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 ADO Recordset

To be able to read database data, the data must first be loaded into a recordset. 

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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
%>

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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
%>

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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
%>