select 
  b.业务员,
  sum(case when 是否付款='是' and datediff(dd,预计付款日期,getdate())=0 then 货值 else  0 end) as '今天预计收款额',
....
from
  a join b
on
  a.业务员=b.业务员
group by
  b.业务员