Getting sql connection string from web.config file

Question

I am learning to write into a database from a textbox with the click of a button. I have specified the connection string to my NorthWind database in my web.config file. However I am not able to access the connection string in my code behind.

This is what I have tried.

protected void buttontb_click(object sender, EventArgs e)
{
    System.Configuration.Configuration rootwebconfig = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("/Mohtisham");
    System.Configuration.ConnectionStringSettings constring;
    constring = rootwebconfig.ConnectionStrings.ConnectionStrings["northwindconnect"];
    SqlConnection sql = new SqlConnection(constring);

    sql.Open();
    SqlCommand comm = new SqlCommand("Insert into categories (categoryName) values ('" + tb_database.Text + "')", sql);
    comm.ExecuteNonQuery();
    sql.Close();
}

I get a tooltip error for

SqlConnection sql = new SqlConnection(constring);

as

System.data.SqlClient.Sqlconnection.Sqlconnection(string) has some invalid arguments.

I want to load the connection string from the web.config in constring

Answer 1

You can simply give a Name to your ConnectionString in web.config file and do this:

web.config:

<add name="ConnectionStringName"  connectionString=YourServer"; Initial Catalog=YourDB; Integrated Security=True"/>

Code Behind:

SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionStringName"].ToString());

Answer 2

That's because the ConnectionStrings collection is a collection of ConnectionStringSettings objects, but the SqlConnection constructor expects a string parameter. So you can't just pass in constring by itself.

Try this instead.

SqlConnection sql = new SqlConnection(constring.ConnectionString);