left join的一个奇怪问题
语句1:select count(*)
from v_gzjbwl_fund_amabzzpay a
left join v_gzjbwl_fund_amabzzbankroll b on (a.member_code = b.member_code and a.fund_billnum = b.fund_billnum
and (b.dd_type_settlement <> '承兑汇票' or b.dd_type_settlement <> '商业承兑汇票')
and b.fund_billnum is not null);
语句2:
select count(*)
from v_gzjbwl_fund_amabzzpay a
left join v_gzjbwl_fund_amabzzbankroll b on (
(b.dd_type_settlement <> '承兑汇票' or b.dd_type_settlement <> '商业承兑汇票') and
a.member_code = b.member_code and a.fund_billnum = b.fund_billnum
and b.fund_billnum is not null);
结果分别为:
906040
822
不知道为什么。。。