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

SELECT DISTINCT a.email FROM `users` a LEFT JOIN `users` b ON a.email = b.email WHERE a.id != b.id;

我没有看到任何JOIN方法，它在复制方面有很多用途。

这种方法会给您带来实际的双倍结果。

SELECT t1.* FROM my_table as t1 
LEFT JOIN my_table as t2 
ON t1.name=t2.name and t1.id!=t2.id 
WHERE t2.id IS NOT NULL 
ORDER BY t1.name

对GROUP BY子句执行SELECT操作。假设name是你想要在其中找到重复项的列:

SELECT name, COUNT(*) c FROM table GROUP BY name HAVING c > 1;

这将返回一个在第一列中包含名称值的结果，以及该值在第二列中出现次数的计数。

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

我更喜欢使用窗口函数(MySQL 8.0+)来查找副本，因为我可以看到整行:

WITH cte AS (
  SELECT *
    ,COUNT(*) OVER(PARTITION BY col_name) AS num_of_duplicates_group
    ,ROW_NUMBER() OVER(PARTITION BY col_name ORDER BY col_name2) AS pos_in_group
  FROM table
)
SELECT *
FROM cte
WHERE num_of_duplicates_group > 1;

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