mysql如何查询重复的数据,去重

SELECT column1, column2, COUNT(*)
FROM table_name
GROUP BY column1, column2
HAVING COUNT(*) > 1;

 

 

-- 假设id是主键或唯一标识
DELETE t1 FROM pv_meter_daily_power t1
INNER JOIN pv_meter_daily_power t2
WHERE
t1.id < t2.id AND
t1.meter_id = t2.meter_id AND
t1.date = t2.date AND
t1.type = t2.type;
-- 保留id较大的记录，删除id较小的重复记录