对sql数据库非空输出的判断+从datagridview中读数据+多表联合sql语句

SELECT     TOP (200) AttendanceId, UserId, OnDutyTime, OffDutyTime, OverTimeStart, OverTimeEnd, RecordTime, 
                      (CASE OverTimeStart WHEN '2000-01-01 00:00:00.000' THEN '未加班' ELSE OverTimeStart END) AS 加班了吗
FROM         AttendanceRecord

 private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
        {           
            this.label8.Text = Convert.ToString(dGV1.Rows[e.RowIndex].Cells["UserId"].Value);
            this.label14.Text = Convert.ToString(dGV1.Rows[e.RowIndex].Cells["NO"].Value);
            this.label9.Text = Convert.ToString(dGV1.Rows[e.RowIndex].Cells["TrueName"].Value);
            this.label10.Text = Convert.ToString(dGV1.Rows[e.RowIndex].Cells["AppDate"].Value);
            this.label11.Text = Convert.ToString(dGV1.Rows[e.RowIndex].Cells["AddTime"].Value);
            this.textBox1.Text = Convert.ToString(dGV1.Rows[e.RowIndex].Cells["ApplyDescription"].Value);
            //DataTable dt = ds.selectNotAllowAppClick(NO);//将Id传进去得到一个数据表
            //if (dt.Rows.Count > 0)
            //{
            //    this.label8.Text = dt.Rows[0]["UserId"].ToString();
            //    this.label9.Text = dt.Rows[0]["TrueName"].ToString();
            //    this.label10.Text = dt.Rows[0]["AppDate"].ToString();
            //    this.label11.Text = dt.Rows[0]["AddTime"].ToString();
            //    this.textBox1.Text = dt.Rows[0]["ApplyDescription"].ToString();
            //    this.label14.Text = Convert.ToString(NO);
            //}
            //else
            //{
            //    MessageBox.Show("此ID不存在!");
            //}
        }

 

 //显示申请加班并加班的记录
        public DataTable selectOvertimeRecordTrue()
        {
            string sql = string.Format("SELECT OvertimeApply.NO, OvertimeApply.UserId, OvertimeApply.TrueName, OvertimeApply.AppDate, OvertimeApply.AddTime FROM OvertimeApply INNER JOIN AttendanceRecord ON OvertimeApply.UserId = AttendanceRecord.UserId AND OvertimeApply.AppDate = AttendanceRecord.RecordTime WHERE (OvertimeApply.State = 1) AND (AttendanceRecord.OverTimeStart <> '2000-01-01 00:00:00.000')");
            DataConn conn = new DataConn(conStr);
            ArrayList paramlist = new ArrayList();
            IDataParameter[] param = (IDataParameter[])paramlist.ToArray(typeof(IDataParameter));
            return conn.testDataTable(sql, param);
        }