Run db query (sql server 2005) with ajax. Is it possible?

Question

I never worked with ajax.

I need to know if it is possible to use ajax to run a query on the db (sql server 2005).

My target is to run a query with refreshin

Answer 1

As MarkusQ has said, it is not possible to do this directly, but you can call a web service or page method to perform the database query and return the result to the client side.

Something like this for a Page Method (this is off the top of my head and untested. I'm also making the assumption you're using asp.net 3.5)

public partial class _Default : Page 
{
  [WebMethod]
  public static string PerformDatabaseQuery()
  {
      using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString)
      {
          using (SqlCommand cmd = con.CreateCommand())
          {
              cmd.CommandText = "SELECT records FROM myTable";
              cmd.CommandType = CommandType.Text;

              con.Open();

              SqlDataReader reader = cmd.ExecuteReader();
              StringBuilder sb = new StringBuilder();

              while (reader.Read())
              {
                   sb.Append((string)reader["records"]); 
                   //May want to do some other formatting here
              }

              return sb.ToString();
          }
      }
  }
}

then call the page method from the client side. I'm going to use jQuery here

$.ajax({
  type: "POST",
  url: "Default.aspx/PerformDatabaseQuery",
  data: "{}",
  contentType: "application/json; charset=utf-8",
  dataType: "json",
  success: function(result) {
    //Do something with the returned data
  }
});

You can call it using JavaScript and the JavaScript proxy class that is generated when you set EnablePageMethods = true on the ScriptManager control.

function CallPerformDatabaseQuery()
{
    PageMethods.PerformDatabaseQuery(onSuccess,onFailed);
}

function onSuccess(result,userContext,methodName)
{
  // Do something with returned data
}

function onFailed(error,userContext,methodName)
{
  alert("An error occurred")
}