SQL语法错误？ 并在我的c＃img url字符串中

Question

Hi I have an sql syntax error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[User] u ON u.UserID = wp.UserID LEFT JOIN Pictures p ON p.UserID = u.UserID WHE' at line 1

My code:

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);

                    }
                }
            }
        }
    }

My database structure:

EDIT:

If i take the brackets out of the User in mysql syntax I then get an error:

Column 'UserID' in where clause is ambiguous

RE EDIT:

adding wp. to UserID in WHERE clause gives a new error:

Index (zero based) must be greater than or equal to zero and less than the size of the argument list.

Im sure this is due to this line:

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

Answer 1

Replace this:

WHERE UserID=

With this:

WHERE wp.UserID=

Answer 2

UserID exists in multiple tables so you have to fully qualify it in the WHERE clause.

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

Answer 3

You use both Picture and User in your query, both of which have a UserId column. You'll need to tell your query which one to use.

Eg.

WHERE wp.UserId = 

EDIT 1

Also,

In your String.Format calls, replace "{1}" with "{0}" . "{1}" tells Format to look for the 2nd value you're passing, not the first (since it's zero based).

EDIT 2

As for the original issue (for completeness' sake), remove the square brackets from around [User] in the SQL in your first line.