mysql - 如何将重复行更改为mysql中的唯一值？

Question

我有一个包含大约 1M 条记录的数据库表。我需要在此表中找到所有重复的名称并使它们唯一。

例如...

Id   Name
-----------
1    A
2    A
3    B
4    C
5    C

应该改成...

Id   Name
-----------
1    A-1
2    A-2
3    B
4    C-1
5    C-2

有没有一种有效的方法可以通过 mysql 查询或过程来做到这一点？

提前致谢！

Answer 1

这有点棘手..我在本地主机上进行了测试，它可以满足您的需求..如果您有任何问题，请告诉我。SQL 小提琴

UPDATE temp t1, 
(
    SELECT 
        id as unique_id, 
        new_name 
    FROM(
        SELECT
          id,
          IF(@ROW = Name, @COUNT, @COUNT := 1),
          CONCAT(Name, ' - ', @COUNT) AS new_name,
          @ROW := Name,
          @COUNT := @COUNT + 1
        FROM temp
        JOIN (SELECT @COUNT := 0, @ROW := "") AS t
        WHERE Name IN(SELECT Name FROM temp
        GROUP BY Name
        HAVING COUNT(Name) > 1)
    ) AS temp_test
) as testing
SET t1.Name = testing.new_name where t1.id = testing.unique_id

最终输出如下所示：图片

---

编辑： 为了性能，这可能会更好

1.首先运行这个查询

SET SESSION group_concat_max_len = 1000000;  -- longer if needed
SET @query1 := (
SELECT 
    GROUP_CONCAT(DISTINCT unique_name) 
FROM temp
JOIN(
    select Name as unique_name
    FROM temp
    GROUP BY name
    HAVING COUNT(Name) > 1
) as t
);

2.然后运行此更新

UPDATE temp t1, 
(
    SELECT 
        id as unique_id, 
        new_name 
    FROM(
        SELECT
          id,
          IF(@ROW = Name, @COUNT, @COUNT := 1),
          CONCAT(Name, ' - ', @COUNT) AS new_name,
          @ROW := Name,
          @COUNT := @COUNT + 1
        FROM temp
        JOIN (SELECT @COUNT := 0, @ROW := "") AS t
        WHERE FIND_IN_SET (`name`, @query1)
    ) AS temp_test
) as testing
SET t1.Name = testing.new_name where t1.id = testing.unique_id

我在我的本地测试了它并且它有效，所以你应该能够让它运行:)

Answer 2

UPDATE    table_x AS upd
    SET   upd.Name = CONCAT(upd.Name, '-', upd.Id)
    WHERE upd.id IN(
                    SELECT    sel.id
                        FROM  table_x AS sel
                        WHERE sel.Name = upd.Name
                          AND sel.Id != upd.Id
                 );

Answer 3

首先，您应该将重复的 Id 存储在临时表中。

---

Drop temporary table if not exist temp;

---

Create temporary table temp (
Select max(id)'id' from table_x group by Name having count(*)>1
);

---

Delete from table_x as x,temp as t where x.id = t.id;

只需重复执行此操作...在为名称字段设置唯一键之后，您将获得唯一行。

Answer 4

一个可读的解决方案

CREATE TEMPORARY TABLE duplicate_names
SELECT name FROM records_table
GROUP BY name
HAVING count(name) > 1;

SET @row_number = 1;
SET @name = '';
CREATE TEMPORARY TABLE duplicates
SELECT 
CASE 
WHEN @name = name THEN @row_number:=@row_number + 1
  ELSE   
    @row_number:=1 
END AS identifier,
@name:=name AS name,id 
FROM
    records_table WHERE name IN (SELECT name FROM duplicate_names)
ORDER BY records_table.name;
    
UPDATE records_table INNER JOIN duplicates 
ON records_table.id = duplicates.id
SET records_table.name = 
CONCAT(duplicates.name,'-',duplicates.identifier);