c# - 指数数组的边界之外

我得到这个错误：
索引超出数组的边界。
代码：

   private void PopulateWallPosts(string userId)
    {

        using (OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite2; User=root; Password=commando;"))
        {
            cn.Open();
            using (OdbcCommand cmd = new OdbcCommand("SELECT wp.WallPostings, p.PicturePath FROM WallPosting wp INNER JOIN User u ON u.UserID = wp.FriendUserID INNER JOIN Pictures p ON p.UserID = u.UserID WHERE wp.UserID=" + userId + " ORDER BY idWallPosting DESC", cn))
            {
                //SELECT idWallPosting, wp.WallPostings, p.PicturePath FROM WallPosting wp LEFT JOIN User u ON u.UserID = wp.UserID LEFT JOIN Pictures p ON p.UserID = u.UserID WHERE wp.UserID=" + userId + " ORDER BY idWallPosting DESC
                using (OdbcDataReader reader = cmd.ExecuteReader())
                {
                    test1.Controls.Clear();

                    while (reader.Read())
                    {

                        System.Web.UI.HtmlControls.HtmlGenericControl div = new System.Web.UI.HtmlControls.HtmlGenericControl("div");
                        div.Attributes["class"] = "test";


                        div.ID = String.Format("{0}", reader.GetString(0)); //idwallposting
                        string id = Convert.ToString(div.ID);
                        //store the div id as a string
                        Image img = new Image();
                        img.ImageUrl = String.Format("{0}", reader.GetString(2)); //p.picturepath
                        img.AlternateText = "Test image";

                        div.Controls.Add(img);
                        div.Controls.Add(ParseControl(String.Format("&nbsp&nbsp " + "{0}", reader.GetString(1)))); //wp.wallpostings
                        div.Attributes.Add("onclick", "confirm_delete(" + id + ");");
                        // send the div id to javascript
                        div.Style["clear"] = "both";
                        test1.Controls.Add(div);

                    }
                }
            }
        }
    }

最佳答案

GetString(2)当您只选择两列时，会显得可疑：

SELECT wp.WallPostings, p.PicturePath FROM ...

因为它是基于0的，所以应该GetString(1)