mysql和MongoDB查重

MongoDB查重：查询proid_1表的perio_id的重复

db.getCollection('proid_1').aggregate([
    { $group: { _id : '$perio_id', count: { $sum : 1 } } },
    { $match: { count: { $gt : 1} } }
])

MySQL查重：查询periodical_list_new表的perio_id的重复
select * from periodical_list_new where perio_id in (select perio_id from periodical_list_new group by perio_id having count(perio_id)>1);