查询、删除重复数据的sql语句 mysql 查询 columnname 有重复的数据，保留 id 最大的一个。select max(id) as id, columnname, count(columnname ) as countnumberfrom tablenamegroup by columnnamehaving countnumber 1order by countnumber desc;删除 colum
查询 、删除重复数据的sql语句 mysql 查询 columnname 有重复的数据，保留 id 最大的一个。select max(id) as id, columnname, count(columnname ) as countnumberfrom tablenamegroup by columnnamehaving countnumber> 1order by countnumber desc;删除 columnname 有重复的数据，保留 id 最小的一个。delete tablename t1from tablename t1, (select min(id) id , columnname from tablename group by columnname having count(1) > 1 ) t2where t1.columnname = t2.columnnameand t1. id > t2.id;