һAccessͳʱҪͳֶָεĺͣʹõSumͳʱָ֣ѯͳʱпܷؿֵNull¶ӦֶʾΪհףӦʾΪ0˼·ڻȡ¼RSжϣȻΪ0ͻȻ뵽iifֲһƪ֮ǰļˣؼ룺
select iif(isnull(sum(ֶ)),0,sum(ֶ)) as ֶα from where
ע as ʡ
һMSSQLһЩģ