php - 仅更新 MySQL 中重复条目的第一条记录

Question

问题解决了!

更新:

不太符合我的需要，让我们在带有字段 ID、NAME、COVER 的简单表上做例子

我有 100 个条目和 100 个名字，有些名字是重复的，但我只想从重复的名字中更新第一个。

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尝试更新数据库中所有重复项的所有第一行，真的很难做到，知道我该怎么做吗？下面是我试图重建的代码，但是这段代码将所有重复项的第一个代码替换为最后一个代码。

架构，我希望它如何在下面工作

ID NAME COVER
1  Max   1
2  Max   0
3  Andy  1
4  Andy  0
5  Andy  0

UPDATE table t
  JOIN (
    SELECT MinID, b.Name LatestName
    FROM table b
    JOIN (
      SELECT MIN(ID) MinID, MAX(ID) MaxID
      FROM table
      GROUP BY tag
      HAVING COUNT(*) > 1
    ) g ON b.ID = g.MaxID
  ) rs ON t.ID = rs.MinID
SET t.Name = LatestName;

Answer 1

根本不清楚你想要什么。也许是这样的:

UPDATE table AS t
  JOIN 
    ( SELECT MIN(ID) MinID
      FROM table
      GROUP BY Name
      HAVING COUNT(*) > 1
    ) AS m 
    ON t.ID = m.MinID
SET t.Cover = 1 ;

---

对于这个(和 future 的)问题，在写问题时请记住:

1. a description of your problem, as clear as possible    --- you have that
2. data you have now (a few rows of the tables)           --- ok, nice
3. the code you have tried                 --- yeah, but better use same names
                                           --- as the data and description above
4. the error you get (if you get an error)      --- doesn't apply here
5. the result you want (the rows after the update in your case)
                                       --- so we know what you mean in case we 
                                       --- haven't understood from all the rest