查询一张表中某两个字段相同的数据
select * from zwfw_region t where (select count(1) from zwfw_region where uniquecoding=t.regioncode and regioncode=t.uniquecoding) and LENGTH(uniquecoding) =6
select * from zwfw_region t where (select count(1) from zwfw_region where uniquecoding=t.regioncode and regioncode=t.uniquecoding) and LENGTH(uniquecoding) =6