php – MySQL：在不破坏外键约束的情况下消除重复行

我有一个填充了规范化地址的客户数据库.有重复.

每个用户都创建了自己的记录,并输入了自己的地址.因此,我们在用户和地址之间建立了一对一的关系：

CREATE TABLE `users` (
  `UserID` INT UNSIGNED NOT NULL AUTO_INCREMENT,`Name` VARCHAR(63),`Email` VARCHAR(63),`AddressID` INT UNSIGNED,PRIMARY KEY (`UserID`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `addresses` (
  `AddressID` INT UNSIGNED NOT NULL AUTO_INCREMENT,`Duplicate` VARCHAR(1),`Address1` VARCHAR(63) DEFAULT NULL,`Address2` VARCHAR(63) DEFAULT NULL,`City` VARCHAR(63) DEFAULT NULL,`State` VARCHAR(2) DEFAULT NULL,`ZIP` VARCHAR(10) DEFAULT NULL,PRIMARY KEY (`AddressID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;  

而数据：

INSERT INTO `users` VALUES
    (1,'Michael','[e-mail]',1),(2,'Steve','[e-mail]',2),(3,'Judy','[e-mail]',3),(4,'Kathy','[e-mail]',4),(5,'Mark','[e-mail]',5),(6,'Robert','[e-mail]',6),(7,'Susan','[e-mail]',7),(8,'Paul','[e-mail]',8),(9,'Patrick','[e-mail]',9),(10,'Mary','[e-mail]',10),(11,'James','[e-mail]',11),(12,'Barbara','[e-mail]',12),(13,'Peter','[e-mail]',13);


INSERT INTO `addresses` VALUES
    (1,'','1234 Main Street','Springfield','KS','54321'),'Y','5678 Sycamore Lane','Upstate','NY','50000'),'1000 State Street','Apt C','Sunnydale','OH','Apt A','1000 Main Street','9999 Valleyview','54321');

哦,是的,让我加上那个外键关系：

ALTER TABLE `users` ADD CONSTRAINT `AddressID` 
FOREIGN KEY `AddressID` (`AddressID`)
REFERENCES `addresses` (`AddressID`);

我们通过第三方服务清理了我们的地址列表,该服务对数据进行了规范化并指出了我们重复的位置.这是Duplicate列的来源.如果有’Y’,则它是另一个地址的副本.主要地址未标记为重复,如示例数据中所示.

我显然想要删除所有重复记录,但有用户记录指向它们.我需要它们指向不重复的地址版本.

那么如何更新用户的AddressID以匹配非重复地址？

我能想到的唯一方法就是使用高级语言迭代所有数据,但我很确定MySQL拥有以更好的方式做这样的事情所需的所有工具.

这是我尝试过的：

SELECT COUNT(*) as cnt,GROUP_CONCAT(AddressID ORDER BY AddressID) AS ids
FROM addresses
GROUP BY Address1,Address2,City,State,ZIP
HAVING cnt > 1;

+-----+--------------+
| cnt | ids          |
+-----+--------------+
|   2 | 5,7          |
|   6 | 1,2,3,6,8,10 |
|   2 | 4,11         |
+-----+--------------+
3 rows in set (0.00 sec)

从那里,我可以遍历每个结果行并执行此操作：

UPDATE `users` SET `AddressID` = 1 WHERE `AddressID` IN (2,10);

但是必须有一个更好的MySQL方式,不应该吗？

一切都说完了,数据应该是这样的：

SELECT * FROM `users`;
+--------+---------+-------------------+-----------+
| UserID | Name    | Email             | AddressID |
+--------+---------+-------------------+-----------+
|      1 | Michael | [e-mail] |         1 |
|      2 | Steve   | [e-mail]   |         1 |
|      3 | Judy    | [e-mail]    |         1 |
|      4 | Kathy   | [e-mail]   |         4 |
|      5 | Mark    | [e-mail]    |         5 |
|      6 | Robert  | [e-mail]  |         1 |
|      7 | Susan   | [e-mail]   |         5 |
|      8 | Paul    | [e-mail]    |         1 |
|      9 | Patrick | [e-mail] |         9 |
|     10 | Mary    | [e-mail]    |         1 |
|     11 | James   | [e-mail]   |         4 |
|     12 | Barbara | [e-mail] |         1 |
|     13 | Peter   | [e-mail]   |        13 |
+--------+---------+-------------------+-----------+
13 rows in set (0.00 sec)

SELECT * FROM `addresses`;
+-----------+-----------+--------------------+----------+-------------+-------+-------+
| AddressID | Duplicate | Address1           | Address2 | City        | State | ZIP   |
+-----------+-----------+--------------------+----------+-------------+-------+-------+
|         1 |           | 1234 Main Street   |          | Springfield | KS    | 54321 |
|         4 |           | 5678 Sycamore Lane |          | Upstate     | NY    | 50000 |
|         5 |           | 1000 State Street  | Apt C    | Sunnydale   | OH    | 54321 |
|         9 |           | 1000 State Street  | Apt A    | Sunnydale   | OH    | 54321 |
|        13 |           | 9999 Valleyview    |          | Springfield | KS    | 54321 |
+-----------+-----------+--------------------+----------+-------------+-------+-------+
5 rows in set (0.00 sec)

救命？

最佳答案

要选择要查看的结果：

SELECT   a.UserID,a.Name,a.Email,(
            SELECT  addressID 
            FROM    addresses c
            WHERE   c.Address1 = b.Address1
            AND     c.Address2 = b.Address2
            AND     c.City = b.City
            AND     c.State = b.State
            AND     c.ZIP = b.ZIP
            AND     DUPLICATE != 'Y'

        ) as AddressID
FROM    users a
JOIN    addresses b
ON      a.AddressID = b.AddressID

这会将users表更新为上面查询中显示的结果.

UPDATE  users a
JOIN    addresses b
ON      a.AddressID = b.AddressID
SET     a.addressID  = 
        (
            SELECT  addressID 
            FROM    addresses c
            WHERE   c.Address1 = b.Address1
            AND     c.Address2 = b.Address2
            AND     c.City = b.City
            AND     c.State = b.State
            AND     c.ZIP = b.ZIP
            AND     Duplicate != 'Y'
        )
WHERE Duplicate = 'Y'

请注意,对于您提供的示例数据,#12 Barbara的ID在SELECT查询中为空,因为她的地址被标记为重复,而实际上它对于提供的列表是唯一的.它与地址1不匹配,如“它应该如何看”结果中所示.

编辑

为了处理不正确的重复标记,例如#12 Barbara,或者可能是其他未标记的重复标记,您可以跳过重复标记列检查并使用ORDER BY&对子查询进行LIMIT,以便它将返回第一个最低匹配地址ID,而不管重复标记如何：

UPDATE  users a
JOIN    addresses b
ON      a.AddressID = b.AddressID
SET     a.addressID = 
        (
            SELECT      addressID 
            FROM        addresses c
            WHERE       c.Address1 = b.Address1
            AND         c.Address2 = b.Address2
            AND         c.City = b.City
            AND         c.State = b.State
            AND         c.ZIP = b.ZIP
            ORDER BY    c.addressID ASC
            LIMIT       1
        )