我是想得出2个表中差异的那部分记录，类似与Python set() - set()那样的效果。不知道有没有简单的法子？
如t1：
t2：
期望结果：
t1 = table(1 2 3 as id, `a `a `b as value) t2 = table(1 2 2 as id, `b `a `c as value) select * from lj(t1, t2, `id`value) where isNull(t2.id)
