主题：SQL连接求助

Select a.*,b.农商行到账,c.奖励2 from ({Sheet2} As a left join {Sheet1} As b on a.报名号 =b.报名号) left join {Sheet3} As c on a.报名号 =c.报名号

Select a.*,b.农商行到账,c.奖励2 from ({Sheet2} As a left join (select 报名号,sum(农商行到账) as 农商行到账 from{Sheet1} group by 报名号) As b on a.报名号 =b.报名号) left join {Sheet3} As c on a.报名号 =c.报名号

这个临时表是怎么生成的？想要怎么改？

a isnot nothing andalso b isnot nothing andalso c isnot nothing andalso (d isnot nothing orelse e isnot nothing)

如果变量是数值型（整数，双精度），改为如：Zub = Nothing

有可能不是空值，而是空字符串，这样判断