sql语句求助
OleDbDataAdapter1.SelectCommand.CommandText = "select '" & zm(i) & "' as 发站,'" & zm(j) & "' as 到站,sum(rs) as 人数 from rs where year(rq)='" & Year(TextBox1.Text) & "' and month(rq)='" & Month(TextBox1.Text) & "' and cc=" & dqcc & " and fz='" & zm(i) & "' And dz ='" & zm(j) & "'"
返回的结果有很多sum(rs)为null的,想去掉,在sql的where子句里怎么实现?