select sum(m.deal_qty)/count(m.deal_qty) as a,sum(m.aveprice_amt)/count(m.aveprice_amt) as b,t.short_str,m.month_datefrom dc_market_tproj_f m left join dc_tproject_d t on m.proj_id = t.proj_idwhere m.proj_id = '5DA8C46D-FF8A-4E7B-A36B-579A1F353BC2' and left(m.month_date,4) = convert(varchar(7),DATEADD(mm, -13, GETDATE()),120)group by month_date,short_strunion allselect sum(f.deal_qty)/count(f.deal_qty) as a,sum(f.aveprice_amt)/count(f.aveprice_amt) as b,'竞品平均' 'short_str',f.month_datefrom dc_cproject_form_d f left join dc_cproject_d c on f.proj_id = c.proj_id where c.tproj_id = '5DA8C46D-FF8A-4E7B-A36B-579A1F353BC2'and left(f.month_date,4) = convert(varchar(7),DATEADD(mm, -13, GETDATE()),120)group by month_dateunion allselect sum(f.deal_qty)/count(f.deal_qty) as a,sum(f.aveprice_amt)/count(f.aveprice_amt) as b,c.proj_str 'short_str',f.month_datefrom dc_cproject_form_d f left join dc_cproject_d c on f.proj_id = c.proj_id where c.proj_str = '${B4}' and month_date >= convert(varchar(7),DATEADD(mm, -13, GETDATE()),120)group by month_date,proj_str怎么在'${B4}'有值的时候使union的第二段失效?