出现表不明确
update cardinfo set preamt=b.curamt from cardinfo a , cardinfo b where a.cardid =b.cardid and a.updatedate = '2007-01-01 ' and b.updatedate =dateadd ( dd , - 1 , '2007-01-01 ' ) ;


[解决办法]
update a --用别名
set
preamt=b.curamt
from
cardinfo a , cardinfo b
where
a.cardid =b.cardid
and
a.updatedate = '2007-01-01 '
and
b.updatedate =dateadd ( dd , - 1 , '2007-01-01 ' )