mysql找出重复的信息

(1)找出重复的信息
SELECT comname FROM (SELECT comname,COUNT(comname) AS times FROM test_bf.`test_table` 
GROUP BY comname) b 
WHERE b.times > 1;
(2)删除重复的信息
delete from  test_bf.`test_table`  where  comname in 
(SELECT comname FROM (SELECT comname,COUNT(comname) AS times FROM test_bf.`test_table` 
GROUP BY comname) b 
WHERE b.times > 1;)


SELECT comname,COUNT(comname) AS times FROM test_bf.`test_table`  GROUP BY comname) b