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
为了获得所有包含复制的数据,我使用了以下方法:
SELECT * FROM TableName INNER JOIN(
SELECT DupliactedData FROM TableName GROUP BY DupliactedData HAVING COUNT(DupliactedData) > 1 order by DupliactedData)
temp ON TableName.DupliactedData = temp.DupliactedData;
TableName =您正在使用的表。
DupliactedData =您正在寻找的重复数据。
其他回答
假设您的表名为TableABC,您想要的列是Col, T1的主键是key。
SELECT a.Key, b.Key, a.Col
FROM TableABC a, TableABC b
WHERE a.Col = b.Col
AND a.Key <> b.Key
与上面的答案相比,这种方法的优点是它给出了Key。
SELECT
t.*,
(SELECT COUNT(*) FROM city AS tt WHERE tt.name=t.name) AS count
FROM `city` AS t
WHERE
(SELECT count(*) FROM city AS tt WHERE tt.name=t.name) > 1 ORDER BY count DESC
SELECT DISTINCT a.email FROM `users` a LEFT JOIN `users` b ON a.email = b.email WHERE a.id != b.id;
作为利维克的答案的一个变体,它可以让你找到重复结果的id,我使用了以下方法:
SELECT * FROM table1 WHERE column1 IN (SELECT column1 AS duplicate_value FROM table1 GROUP BY column1 HAVING COUNT(*) > 1)
要查找Employee中的name列中有多少记录是重复的,下面的查询很有用;
Select name from employee group by name having count(*)>1;