select * from [Sheet1$] where??? 我后面想加个条件  按条件导出需要的内容 
 我该怎么写  
 这里指的是直接在     DataSet ds;
        string Xls_ConnStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + uploadPath + ";Extended Properties='Excel 8.0;HDR=NO;IMEX=1';";
        OleDbConnection Conn = new OleDbConnection(Xls_ConnStr);
        try
        {
            Conn.Open();
            string sql_str = "select * from [Sheet1$] where???";            OleDbDataAdapter da = new OleDbDataAdapter(sql_str, Conn);
            ds = new DataSet();
            da.Fill(ds, "excel_data");
            Conn.Close();
        }
红色区域我想加按条件直接在excel里进行帅选  哪位大侠教教小弟 不知道怎么操纵excel