无法使用C＃更新到.mdb文件

Question

At first I tried this:

    string set = "";
    for (int i = 1; i < result.Count; i++)
    {
        if ((fieldtypes[i] == "System.Int32"))
        {
            set += fields[i] + "=" + result[i] + ", ";
        }
        else if (fieldtypes[i] == "System.String")
        {
            set += fields[i] + "='" + result[i] + "', ";
        }
        else if (fieldtypes[i] == "System.Boolean")
        {
            set += fields[i] + "=" + result[i] + ", ";
        }
        else if (fieldtypes[i] == "System.DateTime")
        {
            set += fields[i] + "='#" + System.DateTime.Now + "#', ";
        }
    }
    set = set.Substring(0, set.Length - 2);
    string sql11 = "UPDATE [Contacts] SET " + set + " WHERE pkContactID=" + cKey;
    OleDbCommand myCommand11 = new OleDbCommand(sql11, myConnection);
    myCommand11.ExecuteNonQuery();

Now this WORKED when I omitted the string and datetime conditions so that it only updated the int and boolean. So it has something to do with a syntax error when I try to update a field where the type is a string.

---

Then I heard that you have to use parameters when writing to an .mdb file, so I tried this:

        string sql11 = "UPDATE [Contacts] SET ";
        for (int i = 1; i < result.Count; i++)
        {
            sql11 += fields[i] + " = ?, ";
        }
        sql11 = sql11.Substring(0, sql11.Length - 2);
        sql11 += " WHERE pkContactID = " + cKey;
        using (myConnection)
        {
            using (OleDbCommand myCommand11 = new OleDbCommand(sql11, myConnection))
            {
                myCommand11.CommandType = CommandType.Text;
                for (int j = 1; j < result.Count; j++)
                {
                    if (fieldtypes[j] == "System.Int32")
                    {
                        myCommand11.Parameters.AddWithValue(fields[j], int.Parse(result[j]));
                    }
                    else if (fieldtypes[j] == "System.String")
                    {
                        myCommand11.Parameters.AddWithValue(fields[j], result[j]);
                    }
                    else if (fieldtypes[j] == "System.Boolean")
                    {
                        myCommand11.Parameters.AddWithValue(fields[j], Boolean.Parse(result[j]));
                    }
                    else if (fieldtypes[j] == "System.DateTime")
                    {
                        myCommand11.Parameters.AddWithValue(fields[j], DateTime.Now);
                    }
                }
                Console.WriteLine(sql11);
                myCommand11.ExecuteNonQuery();
            }
        }
    }

Which did not work either. I don't think the ?'s are being replaced properly.

Anyway, please help me fix it so that I can update properly.

Answer 1

Instead of having to mess around with the UPDATE query string for Access, which is easily prone to syntax errors, I just created a DataTable object and SELECTed the row I wanted to UPDATE. I then updated the table via an array of the elements that I wanted to change, then updated the table back to the server using an adapter. This worked out well without me worrying about the syntax! :)

Cheers