navicat中查重並刪除

# 查詢所有重複的數據

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

# 只顯示某幾個字段  提高查詢速度
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)

# 把查詢出來的重複行刪除
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);