我想在MySQL数据库中取出重复的记录。这可以用:

SELECT address, count(id) as cnt FROM list
GROUP BY address HAVING cnt > 1

结果是:

100 MAIN ST    2

我想要拖动它,以便它显示复制的每一行。喜欢的东西:

JIM    JONES    100 MAIN ST
JOHN   SMITH    100 MAIN ST

有什么想法可以做到吗?我试图避免做第一个,然后在代码中用第二个查询查找重复。


当前回答

 SELECT firstname, lastname, address FROM list
 WHERE 
 Address in 
 (SELECT address FROM list
 GROUP BY address
 HAVING count(*) > 1)

其他回答

我试着用最好的答案来回答这个问题,但它还是把我弄糊涂了。实际上,我只需要在表的一个字段上。下面这个链接的例子对我来说效果很好:

SELECT COUNT(*) c,title FROM `data` GROUP BY title HAVING c > 1;

要快速查看重复的行,可以运行一个简单的查询

在这里,我正在查询表,并列出所有重复的行相同的user_id, market_place和sku:

select user_id, market_place,sku, count(id)as totals from sku_analytics group by user_id, market_place,sku having count(id)>1;

要删除重复的行,必须决定要删除哪一行。例如id较低(通常较旧)或其他日期信息。在我的情况下,我只是想删除较低的id,因为较新的id是最新的信息。

首先仔细检查是否正确的记录将被删除。在这里,我正在选择将被删除的副本中的记录(通过唯一id)。

select a.user_id, a.market_place,a.sku from sku_analytics a inner join sku_analytics b where a.id< b.id and a.user_id= b.user_id and a.market_place= b.market_place and a.sku = b.sku;

然后我运行delete查询来删除dupes:

delete a from sku_analytics a inner join sku_analytics b where a.id< b.id and a.user_id= b.user_id and a.market_place= b.market_place and a.sku = b.sku;

备份,双重检查,验证,验证备份,然后执行。

这里的大多数答案不适用于有多个重复结果和/或有多个列要检查重复的情况。当你在这种情况下,你可以使用这个查询来获得所有重复的id:

SELECT address, email, COUNT(*) AS QUANTITY_DUPLICATES, GROUP_CONCAT(id) AS ID_DUPLICATES
    FROM list
    GROUP BY address, email
    HAVING COUNT(*)>1;

如果希望将每个结果作为一行列出,则需要更复杂的查询。这是我发现有效的方法:

CREATE TEMPORARY TABLE IF NOT EXISTS temptable AS (    
    SELECT GROUP_CONCAT(id) AS ID_DUPLICATES
    FROM list
    GROUP BY address, email
    HAVING COUNT(*)>1
); 
SELECT d.* 
    FROM list AS d, temptable AS t 
    WHERE FIND_IN_SET(d.id, t.ID_DUPLICATES) 
    ORDER BY d.id;

另一个解决方案是使用表别名,如下所示:

SELECT p1.id, p2.id, p1.address
FROM list AS p1, list AS p2
WHERE p1.address = p2.address
AND p1.id != p2.id

在这种情况下,您真正要做的是获取原始的列表表,从中创建两个假装的表——p1和p2,然后在地址列上执行连接(第3行)。第4行确保相同的记录不会在结果集中多次出现(“重复重复”)。

从列表中选择地址where address = any (Select address from (Select address, count(id) CNT from list group by address with CNT > 1) as t1)按地址排序

内部子查询返回具有重复地址的行 外层子查询返回重复地址的地址列。 外层子查询必须只返回一列,因为它被用作操作符'= any'的操作数。