Question

我有4列不同的数字，每行是不同的组合，我的目标是删除删除表中的重复项。由于这些是交换数字顺序的组合，我想删除交换的行并且只保留1（我猜测每个4个数字集将在表格中有24个不同的选项，所以我会这样做需要删除23并且只保留1）

表名：＆＃34; 4numbers＆＃34;

-------------------------
|id | e1 | e2 | e3 | e4 |
-------------------------
| 1 |  1 |  5 |  3 |  7 |
| 2 |  1 |  5 |  7 |  9 |
| 3 |  5 |  1 |  7 |  3 |
-------------------------

所以我需要删除一个有重复组合的行。例如，第1行或第3行之一

这是我尝试过的，但它进入了一个无限循环，我确信我的查询有问题。

<?php

    $sql = mysql_connect("localhost", "root", "mysql");
    if (!$sql) {
        die("Could not connect: " . mysql_error());
    }
    mysql_select_db("combs");

      $result = mysql_query("delete b from 4_even a join 4_even b on (a.e1 = b.e2 and a.e2 = b.e2 and a.e3 = b.e4 and a.e4 = b.e4) or (a.e2 = b.e1 and a.e1 = b.e2 and a.e4 = b.e3 and a.e3 = b.e4) where a.id < b.id;");

      echo "success";
    if (!$result) {
        die("Could not delete. " . mysql_error());
    }

?>

我的查询是我之前使用的另一个查询的改编，用于从2列而不是4列的表中删除重复项，它与它完美配合。所以我只需要调整它以支持4列。

mysql_query("delete b from 4_numbers a join 4_numbers b on (a.e1 = b.e2 and a.e2 = b.e2) or (a.e2 = b.e1 and a.e1 = b.e2) where a.id < b.id;")

Answer 1

你可以使用这样的查询。

1）创建一个临时表 2）在temp中插入所有唯一的行 3）重命名表（原子），因此应用程序不会失败

CREATE  TABLE tmp_4_even LIKE 4_even;

INSERT INTO tmp_4_even
SELECT e2.* FROM (
        SELECT id FROM (
            SELECT min(id) AS id, GROUP_CONCAT(e1 SEPARATOR '-')  AS g
            FROM ( SELECT id,e1  FROM 4_even UNION ALL SELECT id,e2  FROM 4_even UNION ALL SELECT id,e3  FROM 4_even UNION ALL SELECT id,e4  FROM 4_even
            ORDER BY id,e1
        ) AS res
        GROUP BY id
    ) res2
    GROUP BY g 
) e1
LEFT JOIN 4_even e2 ON e1.id = e2.id;

RENAME TABLE 4_even TO 4_even_org, tmp_4_even TO 4_even;

示例内部查询

mysql> SELECT * FROM (
    -> SELECT min(id) AS id, GROUP_CONCAT(e1 SEPARATOR '-')  AS g
    -> FROM ( SELECT id,e1  FROM 4_even UNION ALL SELECT id,e2  FROM 4_even UNION ALL SELECT id,e3  FROM 4_even UNION ALL SELECT id,e4  FROM 4_even
    -> ORDER BY id,e1
    -> ) AS res
    -> GROUP BY id
    -> ) res2
    -> GROUP BY g ;
+------+---------+
| id   | g       |
+------+---------+
|    1 | 1-3-5-7 |
|    4 | 5-7-1-5 |
+------+---------+
2 rows in set, 1 warning (0,00 sec)

mysql>

<强>样品

mysql> select * from 4_even;
+----+------+------+------+------+
| id | e1   | e2   | e3   | e4   |
+----+------+------+------+------+
|  1 |    1 |    5 |    3 |    7 |
|  2 |    1 |    5 |    7 |    3 |
|  3 |    5 |    1 |    7 |    3 |
|  4 |    5 |    1 |    7 |    5 |
+----+------+------+------+------+
4 rows in set (0,00 sec)

mysql> CREATE  TABLE tmp_4_even LIKE 4_even;
Query OK, 0 rows affected (0,02 sec)

mysql>
mysql> INSERT INTO tmp_4_even
    -> SELECT e2.* FROM (
    -> SELECT id FROM (
    -> SELECT min(id) AS id, GROUP_CONCAT(e1 SEPARATOR '-')  AS g
    -> FROM ( SELECT id,e1  FROM 4_even UNION ALL SELECT id,e2  FROM 4_even UNION ALL SELECT id,e3  FROM 4_even UNION ALL SELECT id,e4  FROM 4_even
    -> ORDER BY id,e1
    -> ) AS res
    -> GROUP BY id
    -> ) res2
    -> GROUP BY g
    -> ) e1
    -> LEFT JOIN 4_even e2 ON e1.id = e2.id;
Query OK, 2 rows affected, 1 warning (0,00 sec)
Records: 2  Duplicates: 0  Warnings: 1

mysql>
mysql> RENAME TABLE 4_even TO 4_even_org, tmp_4_even TO 4_even;
Query OK, 0 rows affected (0,00 sec)

mysql> select * from 4_even;
+----+------+------+------+------+
| id | e1   | e2   | e3   | e4   |
+----+------+------+------+------+
|  1 |    1 |    5 |    3 |    7 |
|  4 |    5 |    1 |    7 |    5 |
+----+------+------+------+------+
2 rows in set (0,00 sec)

mysql>

删除我的数据库中包含4列

1 个答案: