刪除和資料庫無關的圖片函數

 zj123.SQLDB.DbAccess dba = new zj123.SQLDB.DbAccess(this.textBox2.Text.Trim());
            //插入暫存資料表資料--對應年月的
            string tempInsertSql = "insert into tempDataFiles([FileName]) select [FileName] from datafiles where [filename] like '%"+this.textBox1.Text.Trim()+"%'";
            string tempDeleteSql = "delete from tempDataFiles";
            dba.GetState(tempDeleteSql + ";" + tempInsertSql + ";");
            StringBuilder sbsql = new StringBuilder("delete from DriveFiles;");
            System.IO.DirectoryInfo dir = new System.IO.DirectoryInfo(this.folderBrowserDialog1.SelectedPath);

            foreach (System.IO.FileInfo fi in dir.GetFiles())
            {
                sbsql.AppendFormat("insert into DriveFiles([FileName],[FilePath]) values('{0}','{1}');",fi.Name,fi.FullName);

            }
            foreach(System.IO.DirectoryInfo di in dir.GetDirectories())
            {
                foreach (System.IO.FileInfo fi in di.GetFiles())
                {
                    sbsql.AppendFormat("insert into DriveFiles([FileName],[FilePath]) values('{0}','{1}');", fi.Name, fi.FullName);

                }

            }
            dba.GetState(sbsql.ToString());
            string tempDeletSql = "select * from DriveFiles where [FileName] not in(select [FileName] from tempDataFiles)";
            DataTable dt = dba.GetTable(tempDeletSql);
            int i = 0;
            int a = dt.Rows.Count;
            foreach (DataRow dr in dt.Rows)
            {
                System.IO.File.Delete(Convert.ToString(dr["FilePath"]).Trim());
                i++;
                this.label4.Text = "正在刪除" + i.ToString()+"---共"+a.ToString().ToString();
                Application.DoEvents();
            }