Tip

A simple database access component

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We all use components and databases these days. Hence, I thought, why not make a generic component that everybody can use? Yes, you can actually use this component for database access. You can connect to any database with a valid connection string and pass any valid SQL statement. The method DataReader takes two arguments:

  1. DBString (the database connection string)
  2. SQL (the SQL statement)

The component returns to you an ADO DataReader, which you can databind to a ASP Datagrid. Here is the code for the component (DBAccess.cs):

Namespace DBAccess 
 { 
using System; 
using System.Data; 
using System.Data.ADO; public
class DBRead 

{ 
public ADODataReader DataReader(string DBStr,string
strSQL) 

{ 
  // Create the connection 
ADOConnection oCn = new ADOConnection(DBStr);
//Create the Command Object 
ADOCommand oCm =   new ADOCommand(strSQL,oCn);
//Open the connection 
oCn.Open(); 
//Create a null DataReader Object 
ADODataReader oDr ; 
//Execute the SQL Query 
oCm.Execute(out oDr); 
// Return the DataReader 
return oDr; 
} 
} 
}

You can compile the above code with the following command:

csc /r:System.Data.dll /t:library DBAccess.cs

We have imported the System.Data NameSpace in our component, now we need to give its reference. Here is the ASP.NET code (Client.aspx):

<%@Page language= "c#" AutoEventWireup="false" debug= "true" %>
<%@ Import NameSpace= "DBAccess"%>
<%@ Import NameSpace= "System.Data"%>
<%@ Import NameSpace= "System.Data.ADO"%> 
<script language=c#" runat="server" >
protected void Submit_OnClick(Object s, EventArgs e) 
{ 
// Create an instance of our component 
DBAccess.DBRead oDBr = new DBAccess.DBRead(); 
//Create a null DataReader 
ADODataReader oDr; 
// Use the DataReader Method of our component
oDr = oDBr.DataReader(dbstr.Text,SQL.Text); 
// DataBind the DataReader with the DataGrid 
oDg.DataSource = oDr; 
oDg.DataBind(); 
} 
</script>
<html>
<head> 
<meta name="GENERATOR" Content="Microsoft Visual Studio 7.0"> 
<meta name="CODE_LANGUAGE" Content="C#"> 
</head>
<body> 
<form method="post" runat="server"> 
DB String : <asp:textbox id="dbstr" runat="Server"/><br/> 
SQL Query : <asp:textbox id="SQL" runat="Server"/><br/> 
<asp:button text="Submit" runat="Server" onclick="Submit_OnClick"/> 
<br/> 
<ASP:DataGrid id="oDg" runat="server" 
BackColor="#ccccff" 
BorderColor="black" 
ShowFooter="false" 
CellPadding=3 
CellSpacing="0" 
Font-Size="9pt" 
HeaderStyle-BackColor="#aaafff" 
Headerstyle-font-bold 
/>
</form>
</body>
</html>

You don't have to separately compile the ASP.NET client. It automatically gets compiled with the first request. Happy coding!


Source: DotNetExtreme.com

This was first published in August 2003

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