select * from (select top 1 a from A) a,(select top 1 b from B where xx='xx') b的问题
1 select * from (select top 1 a from A) a,(select top 1 b from B where xx='xx') b
a b
1 2
(select top 1 a from A) a 总有记录
(select top 1 b from B where xx='xx') b
它如果没有记录的话,语句1也不出来记录,,这是咋回事泥