Below is the most simple database query for C# to populate a GridView object:

            int nItemID = 1;
            try
            {
                using (SqlConnection oSQLConn = 
                   new SqlConnection(ConfigurationManager.ConnectionStrings["UserInfo"].ConnectionString))
                {
                    oSQLConn.Open();
                    using (SqlCommand oSQLCmd = new SqlCommand())
                    {
                        oSQLCmd.Connection = oSQLConn;
                        oSQLCmd.CommandText = "SELECT DisplayName, EMail FROM Users WHERE UserID = @PARAM_ItemID";
                        oSQLCmd.Parameters.AddWithValue("@PARAM_ItemID", nItemID);
                        SqlDataReader oSQLReader = oSQLCmd.ExecuteReader();
                        GridView1.DataSource = oSQLReader;
                        GridView1.DataBind();
                    }
                }
            }
            catch (Exception ex)
            {
                Label_ErrorMsg.Text = ex.Message;
            }

There are actually many reasons to never use this, including performance, caching, safe SQL, code reuse, standards, proper exception handling, etc, etc.  But sometimes you need a quick and dirty, non-production, piece of code for testing and/or development.  This is it.