摘要：
1、查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断select*frompeoplewherepeopleIdin(selectpeopleIdfrompeoplegroupbypeopleIdhavingcount(peopleId)>1)例二：select*fromtesttablewherenumeber in (selectnumberfrompeoplegroup bynumberhaving count(number) > 1 )可以查出testtable表中number相同的记录2、删除表中多余的重复记录，重复记录是根据单个字段（people 阅读全文