c# - sql语法错误？在我的 c# img url 字符串中

Question

嗨，我有一个 sql 语法错误:

您的 SQL 语法有错误；检查与您的 MySQL 服务器版本相对应的手册，了解在第 1 行的“[User] u ON u.UserID = wp.UserID LEFT JOIN Pictures p ON p.UserID = u.UserID WHE”附近使用的正确语法

我的代码:

using (OdbcCommand cmd = new OdbcCommand("SELECT 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 UserID=" + userId + " ORDER BY idWallPosting DESC", cn))
            {
                //("SELECT 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 UserID=" + userId + " ORDER BY idWallPosting DESC", cn))
                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.Style["float"] = "left";

                        div.ID = "test";
                        Image img = new Image();
                        img.ImageUrl = String.Format("{1}", reader.GetString(0));
                        // this line needs to be represented in sql syntax
                        img.AlternateText = "Test image";

                        div.Controls.Add(img);
                        div.Controls.Add(ParseControl(String.Format("{0}", reader.GetString(0))));
                        div.Style["clear"] = "both";
                        test1.Controls.Add(div);

                    }
                }
            }
        }
    }

我的数据库结构:

编辑:

如果我在 mysql 语法中将括号从 User 中取出，则会收到错误:

where 子句中的“UserID”列不明确

重新编辑:

添加wp. WHERE 子句中的 UserID 出现新错误:

索引(从零开始)必须大于或等于零且小于参数列表的大小。

我确定这是由于这一行:

img.ImageUrl = String.Format("{1}", reader.GetString(0));

Answer 1

UserID 存在于多个表中，因此您必须在 WHERE 子句中完全限定它。

          V
... WHERE wp.UserID= ...
          ^