gridview 导出dbf

Question

    public static string ExDBF(GridView gr, string tname, string fname)
    {
        string sp = HttpContext.Current.Request.MapPath("~/Excel");
        if (System.IO.File.Exists(sp + "/" + fname))
            System.IO.File.Delete(sp + "/" + fname);
        string newname = sp + "/" + fname;        //构造sql 语句，建立数据表
        string sql = @"create table [" + newname + "](i int(10)";
        string s1 = "insert into [" + newname + "](i";
        for (int i = 0; i < gr.Columns.Count; i++)
        {
            sql = sql + "," + gr.Columns[i].HeaderText + " char(254)";
            s1 = s1 + "," + gr.Columns[i].HeaderText;
        }
        sql = sql + ")";
        s1 = s1 + ") values(";
        //采用odbc导入数据
        string strc = @"Driver={Microsoft Visual Foxpro Driver};sourcetype=DBF;sourceDB=" + sp + "/" + ";Exclusive=No;NULL=NO;Collate=Machine;BACKGROUNDFETCH=NO;DELETED=NO";
        using (System.Data.Odbc.OdbcConnection cn = new System.Data.Odbc.OdbcConnection(strc))
        {
            System.Data.Odbc.OdbcCommand odm = new System.Data.Odbc.OdbcCommand(sql, cn);
            try
            {
                if (cn.State != System.Data.ConnectionState.Open) cn.Open();
                odm.ExecuteNonQuery();
                foreach (GridViewRow r in gr.Rows)
                {
                    string s2 = s1 + (r.RowIndex + 1).ToString();
                    for (int j = 0; j < gr.Columns.Count; j++)
                    {
                        s2 = s2 + ",'" + r.Cells[j].Text.ToString().Replace("&nbsp;", "") + "'";
                    }
                    s2 = s2 + ")";
                    System.Data.Odbc.OdbcCommand odm1 = new System.Data.Odbc.OdbcCommand(s2, cn);
                    odm1.ExecuteNonQuery();
                }
            }
            catch (Exception e)
            {
                TLCWebLib.CTLEvent.logError("CExpExcel:ExExcel" + e.Message + "s2");
            }
            finally
            {
                odm.Dispose();
                cn.Close();
                odm.Dispose();
            }
            return "~/Excel/" + fname;
        }
    }执行到红色部分就报ERROR [42000] [Microsoft][ODBC Visual FoxPro Driver]Command contains unrecognized phrase/keyword.错误，而且怎样存储长度超过255的数据呢？请高人指点！！！！