title: Connect to PostgreSQL using VB.NET, AJAX and NPGSQL
body: <p>I am trying to write a script in VB.NET and/or .asp that will connect to my PostgreSQL database using the NPGSQL data provider. </p>
  
  <p>This function uses AJAX to get a value (selectedFT) and send that value to the helloWorld.asp script.  This part works fine. </p>
  
  <pre><code>function ajaxyThing (selectedFT) {
  
  var xmlhttp; //CREATE THE VARIABLE TO HOLD THE XMLHTTPRequest OBJEcT
  if (window.XMLHttpRequest)
    {// code for IE7+, Firefox, Chrome, Opera, Safari THESE BROWSERS SUPPORT THE   XMLHTTPRequest OBJECT
    xmlhttp=new XMLHttpRequest();  //CREATE THE XMLHTTPRequest OBJECT
    }
  else
   {// code for IE6, IE5 THESE BROWSERS DO NOT SUPPORT THE XMLHTTPRequest OBJECT AND NEED    AND ACTIVEXOBJECT
    xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); //CREATE THE ActiveXObject
    }
  //When using Async = true specify a function to execute when the reponse is ready in     the onreadystatechange event
  xmlhttp.onreadystatechange = function () {
  if (xmlhttp.readyState == 4 &amp;&amp; xmlhttp.status == 200) {
      document.getElementById("responseText").innerHTML = xmlhttp.responseText;
  }
  }
  
  //TO SEND A REQUEST TO A SERVER, WE USE THE open() AND send() METHODS OF THE     XMLHttpRequest object
  xmlhttp.open("GET", "helloWorld.asp?q="+ selectedFT, true);
  xmlhttp.send();
  }
  </code></pre>
  
  <p>Next I need the ASP script (or an .aspx, or an .ashx. I don't know what is the best way) to use the selectedFT value to query my PostgreSQL database. This is where I run into trouble. I know I need to do the following things but I don't know how to put it all together:</p>
  
  <p>1) Get the value from the AJAX http request. For example I should probably use:</p>
  
  <pre><code>response.expires=-1
  q= request.querystring("q")
  </code></pre>
  
  <p>2) Then I need to establish the connection to the PostgreSQL database. I use the following code (taken from this website <a href="http://www.techrepublic.com/article/easily-integrate-postgresql-with-net/6102826" rel="nofollow">http://www.techrepublic.com/article/easily-integrate-postgresql-with-net/6102826</a>) to run in the PageLoad of a standard .aspx page and it works fine to bind the data to a gridview. But what I really need is not to connect the result set to a gridview but have my connection script stand alone so I can use the output to do many different things.   I am not sure how to implement this code in an .asp script (or .aspx, or .ashx) and make it run when I call the .asp script (or .aspx or .ashx) from my AJAX function.</p>
  
  <pre><code> Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)Handles MyBase.Load
  
      Dim pgConnection As NpgsqlConnection = New NpgsqlConnection
      Dim pgCommand As NpgsqlCommand = New NpgsqlCommand
      Dim pgConnectionString As String
      Dim sda As NpgsqlDataAdapter
  
      Dim ds As DataSet
      ds = New DataSet
  
      pgConnectionString = "Server=localhost;Port=5432;Userid=myUserId;Database=myDatabaseName;password=myPassword;Protocol=3;SSL=false;Pooling=true;MinPoolSize=1;MaxPoolSize=20;Encoding=UNICODE;Timeout=15;SslMode=Disable"
      pgConnection.ConnectionString = pgConnectionString
      pgConnection.Open()
      pgCommand.Connection = pgConnection
      pgCommand.CommandType = CommandType.Text
  
      pgCommand.CommandText = "SELECT * FROM ""myTable"";"
  
      If pgConnection.FullState = ConnectionState.Open Then
          MsgBox("Connection To PostGres is open", MsgBoxStyle.MsgBoxSetForeground)
      End If
  
      sda = New NpgsqlDataAdapter(pgCommand)
      sda.Fill(ds)
      GridView1.DataSource = ds
      GridView1.DataBind()
  
      pgConnection.Close()
  End sub
  </code></pre>
  
  <p>Any suggestions would be greatly appreciated. Thanks! </p>