title: Checking if a datatable is null
body: <p>The following code is what I've been using to retrieve user information from a sql database.</p>
  
  <pre><code>            string userName = LoginUser.UserName;
              string password = LoginUser.Password;
              string comm = "SELECT Username,Password,Clientname,Role FROM Users WHERE Username = '" + userName + "';";
              bool rememberUserName = LoginUser.RememberMeSet;
  
              SqlConnection conn = new SqlConnection(connstring);
              conn.Open();
  
              SqlCommand command = new SqlCommand(comm, conn);
              SqlDataAdapter da = new SqlDataAdapter(command);
              DataTable dt = new DataTable();
              da.Fill(dt);
              DataRow dr = dt.NewRow();
              if (dt != null)
              {
                  //logic
              }
  </code></pre>
  
  <p>However, (dt != null) does not return false when there is no entry in the database with the username equal to LoginUser.Username. Is there a different way to check whether or not the sqlcommand is successful?</p>