SQL高手请进：sql能在access里执行，在代码曝“无效的null使用”，即查不出结果出来

string queryStringRgt = @"SELECT TB_YWDA.ywda_SeqNO as 顺序号, TB_YWDAJ.ywdaj_DirName as 档号, TB_YWDAJ.ywdaj_KeepPeriod as 保管期限, TB_YWDAJ.ywdaj_Year as 年度, "

                    + " TB_YWDA.ywda_Responsible as 责任者, TB_YWDA.ywda_Title as 题名, TB_YWDA.ywda_PageNO as 页号, TB_YWDAJ.ywdaj_Type as 档案类别, "

                    + " TB_YWDA.ywda_PageSum as 页数,  TB_YWDA.ywda_CreatedTime as 成文时间, TB_YWDA.ywda_ID, TB_YWDA.ywdaj_ID FROM TB_YWDA left join TB_YWDAJ on TB_YWDA.ywdaj_ID = TB_YWDAJ.ywdaj_ID  where CInt(TB_YWDA.ywdaj_ID) = '" + selectedYwdajID + "'";

OleDbCommand SQLQuery = new OleDbCommand();

            DataTable data = new DataTable();

            

            this.skinDataGridViewRgt.DataSource = null;

            SQLQuery.Connection = null;

            OleDbDataAdapter dataAdapter = null;

            this.skinDataGridViewRgt.Columns.Clear(); // <-- clear columns

            //---------------------------------       

            SQLQuery.CommandText = sqlQueryString;

            SQLQuery.Connection = dataBase;

            dataAdapter = new OleDbDataAdapter(SQLQuery);

            MessageBox.Show("hah");

            dataAdapter.Fill(data);          //问题出在这一行

            skinDataGridViewRgt.DataSource = data;