# 查询所有重复的数据

SELECT * FROM hao123 WHERE ir_url IN

(SELECT ir_url FROM `hao123` GROUP BY ir_url having count(ir_url)>1)

# 只显示某几个字段  提高查询速度
SELECT ir_title,ir_url FROM hao123 WHERE ir_url IN
(SELECT ir_url FROM `hao123` GROUP BY ir_url having count(ir_url)>1)

# 把查询出来的重复行删除

DELETE FROM `hao123` WHERE ir_url IN

(SELECT ir_url FROM

(SELECT ir_url FROM `hao123` GROUP BY ir_url having count(ir_url)>1)a)

AND ir_id NOT IN

(SELECT * FROM

(SELECT min(ir_id) FROM `hao123` GROUP BY ir_url HAVING count(ir_url)>1)b);