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

SELECT * 
FROM `dps` 
WHERE pid IN (SELECT pid FROM `dps` GROUP BY pid HAVING COUNT(pid)>1)

其他回答

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

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

下面的代码将找到所有使用了不止一次的product_id。每个product_id只能得到一条记录。

SELECT product_id FROM oc_product_reward GROUP BY product_id HAVING count( product_id ) >1

代码取自:http://chandreshrana.blogspot.in/2014/12/find-duplicate-records-based-on-any.html

SELECT varchar_col
FROM table
GROUP BY varchar_col
HAVING COUNT(*) > 1;

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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