ADO Display Data

Welcome to The Coding College! Displaying data from a database is a core functionality for any web application. With ActiveX Data Objects (ADO) in Classic ASP, this task becomes seamless. In this tutorial, you’ll learn how to fetch and display database records efficiently using ADO.

Why Use ADO to Display Data?

ADO simplifies interaction with databases, making it easy to:

  • Fetch and render data dynamically on web pages.
  • Work with multiple database types like SQL Server, Access, and Oracle.
  • Provide interactive and user-friendly data displays.

Setting Up Your Environment

Before diving into displaying data, ensure you have:

  1. A database ready (e.g., SQL Server, Access).
  2. Classic ASP enabled on your web server.
  3. An understanding of ADO database connections. (Refer to ADO Database Connection for help.)

Steps to Display Data Using ADO

1. Establish a Connection to the Database

To fetch data, first connect to your database using the ADO Connection object.

Example:

Dim conn
Set conn = Server.CreateObject("ADODB.Connection")
conn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("database.mdb")

2. Create and Open a Recordset

A Recordset stores the results of a database query. Use it to retrieve data for display.

Example:

Dim rs, sql
Set rs = Server.CreateObject("ADODB.Recordset")

sql = "SELECT * FROM Users"
rs.Open sql, conn

3. Display Data on the Web Page

Use the Recordset object to iterate through the rows and display data.

Example:

<%
Dim conn, rs, sql

Set conn = Server.CreateObject("ADODB.Connection")
conn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("database.mdb")"

Set rs = Server.CreateObject("ADODB.Recordset")
sql = "SELECT Name, Email FROM Users"
rs.Open sql, conn

Response.Write "<table border='1'>"
Response.Write "<tr><th>Name</th><th>Email</th></tr>"

While Not rs.EOF
    Response.Write "<tr>"
    Response.Write "<td>" & rs("Name") & "</td>"
    Response.Write "<td>" & rs("Email") & "</td>"
    Response.Write "</tr>"
    rs.MoveNext
Wend

Response.Write "</table>"

rs.Close
conn.Close
Set rs = Nothing
Set conn = Nothing
%>

Formatting the Display

To make your data display user-friendly, you can use CSS for styling.

Enhanced Example:

<style>
  table {
    width: 100%;
    border-collapse: collapse;
  }
  th, td {
    border: 1px solid #ddd;
    padding: 8px;
    text-align: left;
  }
  th {
    background-color: #f2f2f2;
  }
</style>

Combine the above styles with the previous ASP code for a polished data table.

Handling Large Data Sets

For large data sets, consider:

  1. Pagination: Split records into pages for better performance.
  2. Search Filters: Allow users to search and filter results dynamically.

Example: Simple Pagination

<%
Dim pageSize, currentPage, startRow, endRow
pageSize = 10 ' Number of records per page
currentPage = Request.QueryString("page")
If IsEmpty(currentPage) Or currentPage = "" Then currentPage = 1
startRow = (currentPage - 1) * pageSize + 1
endRow = currentPage * pageSize

Dim rowNum
rowNum = 0

rs.Open sql, conn
While Not rs.EOF
    rowNum = rowNum + 1
    If rowNum >= startRow And rowNum <= endRow Then
        Response.Write "<tr>"
        Response.Write "<td>" & rs("Name") & "</td>"
        Response.Write "<td>" & rs("Email") & "</td>"
        Response.Write "</tr>"
    End If
    rs.MoveNext
    If rowNum = endRow Then Exit While
Wend
%>

Error Handling

Always include error-handling mechanisms to deal with unexpected issues.

Example:

On Error Resume Next

sql = "SELECT * FROM NonExistentTable"
rs.Open sql, conn

If Err.Number <> 0 Then
    Response.Write "Error: " & Err.Description
    Err.Clear
End If

On Error GoTo 0

Best Practices

  • Optimize SQL Queries:
    • Fetch only the required columns and rows.
SELECT Name, Email FROM Users WHERE Active = 1
  • Close Connections:
    • Always release resources after use.
rs.Close
conn.Close
Set rs = Nothing
Set conn = Nothing
  • Use CSS for Styling:
    • Enhance user experience with a visually appealing design.
  • Sanitize User Input:
    • Protect against SQL injection by validating user input.

Conclusion

With ADO, displaying data dynamically on your website becomes simple and efficient. By mastering the techniques outlined in this guide, you can build feature-rich, data-driven web pages effortlessly.

For more tutorials, tips, and coding resources, explore The Coding College—your trusted destination for programming insights.

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