1、表中多条记录中A字段、B字段有重复的，以ID为key，做数据清理，A、B字段重复的只保留一条：
delete from table1 where ID is not in ( select min(ID) as ID from table1 group by A,B )
其中：select min(ID) as ID from table1 group by A,B： 筛选出根据A、B分组后最小的ID集合
