我有一个varchar列的表,我想找到在这个列中有重复值的所有记录。我可以使用什么查询来查找重复项?
当前回答
CREATE TABLE tbl_master
(`id` int, `email` varchar(15));
INSERT INTO tbl_master
(`id`, `email`) VALUES
(1, 'test1@gmail.com'),
(2, 'test2@gmail.com'),
(3, 'test1@gmail.com'),
(4, 'test2@gmail.com'),
(5, 'test5@gmail.com');
QUERY : SELECT id, email FROM tbl_master
WHERE email IN (SELECT email FROM tbl_master GROUP BY email HAVING COUNT(id) > 1)
其他回答
试着使用这个查询:
SELECT name, COUNT(*) value_count FROM company_master GROUP BY name HAVING value_count > 1;
如果要删除具有多个字段的重复行,首先将它们取消为唯一不同的行指定的新唯一键,然后使用group by命令删除具有相同新唯一键的重复行:
Create TEMPORARY table tmp select concat(f1,f2) as cfs,t1.* from mytable as t1;
Create index x_tmp_cfs on tmp(cfs);
Create table unduptable select f1,f2,... from tmp group by cfs;
进一步采取@maxyfc的答案,我需要找到所有返回的重复值的行,这样我就可以在MySQL Workbench中编辑它们:
SELECT * FROM table
WHERE field IN (
SELECT field FROM table GROUP BY field HAVING count(*) > 1
) ORDER BY field
如果你想删除重复使用DISTINCT
否则使用这个查询:
SELECT users.*,COUNT(user_ID) as user FROM users GROUP BY user_name有用户>
SELECT *
FROM `dps`
WHERE pid IN (SELECT pid FROM `dps` GROUP BY pid HAVING COUNT(pid)>1)