摘要： select value from temp_a awhere a.id between 1 and 100and not exists(select * from temp_b b where a.value=b.value);这时能查出结果select value from temp_a awhere a.id between 1 and 100and a.valuenot in(select valuefrom temp_b);此时查出的结果为空.经过google终于找出原因: 内表(temp_b)有空值. 用not in得到的结果集都为空.以下是结论:1、对于not exists查询， 阅读全文