Question

how to open the btnSMS.PostBackUrl with a new tab / new window? Or is there anyway to go to that URL then automatically go to another page?

More information: That URL is a method to send SMS using service provider (Clickatell). But the URL got nothing other than stating if the message send was successful or not. I don’t want the user who use my ASP.NET to stuck there. I want to allow them to go back to my website after sending the message.

protected void btnSMS_Click1(object sender, EventArgs e)
{

    String HP = txtHP.Text;
    String URL = "http://api.clickatell.com/http/sendmsg?user=myuser&password=mypassword&api_id=myapi_id&to=";
    String Text = "&text=" + txtSMS.Text;
    btnSMS.PostBackUrl = URL + HP + Text;

    string username;
    //Sql Connection to access the database
    SqlConnection conn6 = new SqlConnection("MY CONNECTION");
    //Opening the Connnection
    conn6.Open();
    string mySQL;
    username = HttpContext.Current.User.Identity.Name;
    //Insert the information into the database table Login
    mySQL = "INSERT INTO Table_Message(Username, Message, Title, SendTo) VALUES('" + username + "','" + txtSMS.Text.Trim() + "','" + txtTitle.Text.Trim() + "','" + txtHP.Text.Trim() + "')";

    SqlCommand cmdAdd = new SqlCommand(mySQL, conn6);
    //Execute the sql command
    cmdAdd.ExecuteNonQuery();
    //Close the Connection
}

Answer 1

Your button should closely reflect as below:

<asp:Button runat="server" ID="btnSMS"  UseSubmitBehavior="false"  OnClick="btnSMS_Click1"  Text="Send/> 

Then in the code-behind build your postback url and then after the submition add the following:

protected void btnSMS_Click1(object sender, EventArgs e)
        {


 String HP = txtHP.Text;
            String URL = "http://api.clickatell.com/http/sendmsg?user=myuser&password=mypassword&api_id=myapi_id&to=";
            String Text = "&text=" + txtSMS.Text;
            string UrlFinal = URL + HP + Text;

            string username;
            //Sql Connection to access the database      
            SqlConnection conn6 = new SqlConnection("Data Source=19-17\\sqlexpress;" + "Initial Catalog = Suite2; Integrated Security =SSPI");
            //Opening the Connnection      
            conn6.Open();
            string mySQL;
            username = HttpContext.Current.User.Identity.Name;
            //Insert the information into the database table Login      
            mySQL = "INSERT INTO Table_Message(Username, Message, Title, Startdate, Enddate, SendTo) VALUES('" + username + "','" + txtSMS.Text.Trim() + "','" + txtTitle.Text.Trim() + "','" + txtHP.Text.Trim() + "')";

            SqlCommand cmdAdd = new SqlCommand(mySQL, conn6);
            //Execute the sql command      
            cmdAdd.ExecuteNonQuery();
            //Close the Connection 

            this.ClientScript.RegisterStartupScript(this.GetType(),
                                        "navigate",
                                        "window.open('" + UrlFinal + "');",
                                        true); 

        }

This should open in a new windows. Alternatively one can use window.navigate as well which will open another page in the same browser.