Question

我有一个带有注册的MySQL表，如下所示：

id  name  email            phone   
1   Jim   jim@gmail.com    111  
2   Jim   jim@hotmail.com  111  
3   Fred  fred@gmail.com   222   
4   Fred  fred@gmail.com   222
5   Adam  adam@gmail.com   333

现在，我需要找到已注册的所有不同人员，并且可以通过电子邮件或电话价值执行此操作。我想有一个映射的表/视图。如何根据上面的示例表获得如下所示的类似结果？

person_id  registration_id   
1          1  
1          2
2          3
2          4
3          5

请注意，不需要将id值完全相同。我可以很好地重复使用注册表中的值或生成不同的ID。

Answer 1

可以通过简单的查询来实现：

select min(a.id) as person_id,b.id as registration_id 
from
registrations a
join registrations b on ((a.email=b.email or a.phone=b.phone) and a.id<=b.id)
group by b.id

请在http://sqlfiddle.com/#!9/d61bd/11

验证结果

Answer 2

此查询将为每个注册ID返回第一个person_id（基于相同的r1.phone或r1.email）：

SELECT
  MIN(r2.id) AS person_id,
  r1.id AS registration_id
FROM
  registrations r1 LEFT JOIN registrations r2
  ON r1.email=r2.email OR r1.phone=r2.phone
GROUP BY
  r1.id

现在我们只需要给出排名，但MySQL本身不支持它，我们必须使用带变量的查询：

SELECT
  CASE
    WHEN @l = min_person_id THEN @r
    WHEN @l := min_person_id THEN @r := @r +1
  END AS person_id,
  registration_id
FROM (
  SELECT
    MIN(r2.id) AS min_person_id,
    r1.id AS registration_id
  FROM
    registrations r1 LEFT JOIN registrations r2
    ON r1.email=r2.email OR r1.phone=r2.phone
  GROUP BY
    r1.id
) s, (SELECT @r := 0, @l := NULL) r
ORDER BY
  min_person_id

请看小提琴here。

具有公共值的记录的映射视图

2 个答案: