Object reference not set to an instance of an object, on SqlConnection.Open(), asp.net

Question

just learning asp.net with c# and my code is throwing this exception when im trying to open a connection to my database:

string connectionString ="DataSource=localhost,3306;Database=somedatabase;Uid=username;Pwd=password;";
using(SqlConnection con = new SqlConnection(connectionString))
{
    con.Open(); // Exception Thrown Here
}

Seems relatively simple, so ive really no clue why this is happening.

one other thing;

all this code is inside tags on the webpage (not really sure if that makes any difference, quite new to asp.net)

Cheers!

edit-

Hey, here is the rest of it. Im going to investigate habib's solution.

I am missing some assemblies (mysql), but ill get back when ive tried it out.

<%@ Language=C# %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<%@ Import Namespace="MySql" %>

<HTML>
   <script runat="server" language="C#">
   void MyButton_OnClick(Object sender, EventArgs e)
   {

   }

        void Page_Load(Object sender, EventArgs e)
           {
                // GET THE USERNAME AND PASSWORD FROM THE CLIENT
                NameValueCollection nvc = Request.Form;

                string username = nvc["username"];
                string password = nvc["password"];
                Login(username, password);
           }

           void Login(string username, string password)
           {
                string connectionString = "Data Source=localhost,3306;Database=something;Uid=somename;Pwd=somepass;";
                using(MySqlConnection con = new MySqlConnection(connectionString))
                {
                    con.Open();
    /*
                if (con.State != ConnectionState.Open)
                    return;

                try
                {
                    SqlDataReader   reader = null;
                    SqlCommand      command = new SqlCommand("SELECT * FROM accounts WHERE username=@username AND password=@password", con);

                    reader = command.ExecuteReader();
                    Response.Write(reader[0]);
                }
                catch (Exception e)
                {
                    Response.Write(e.ToString());
                }

                con.Close();*/
        }
        }

I try to create a SqlConnection with this connectionstring and return this error "There is no support for the keyword: 'datasource'." — renefc3
– renefc3, Commented Sep 5, 2013 at 17:11
Just looking at your snippet above, what really stood out to me was the comma in your connection string after localhost. make sure your connection string is well formed: connectionstrings.com/mysql — iamkrillin
– iamkrillin, Commented Sep 6, 2013 at 2:31

Habib · Accepted Answer · 2013-09-05 17:08:43Z

2

You are trying to open MySQL database connection through SqlConnection, Use MySql.Data.MySqlClient.MySqlConnection

SqlConnection class is used for SQL Server connection.

edited Sep 5, 2013 at 17:08

answered Sep 5, 2013 at 17:01

Habib

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4 Comments

usr Over a year ago

Does not explain the nullref exception.

Habib Over a year ago

@usr, I guess its because the OP is specifying a MySQL Connection string, the constructor for SqlConnection is returning null, hence the object con is null, BUT I am not sure about it.

usr Over a year ago

A ctor never returns null, and the BCL should never crash internally. Very rare.

usr Over a year ago

Seeing the updated comment by the OP, this is likely to be the solution. He probably has other funky stuff in his code that is not visible.

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