使用子查询组合 2 个 mysql 查询

Question

我想知道这里是否有人可以帮助解决我遇到的问题。我正在尝试使用子查询将 2 个 mysql 查询合并为一个查询。我目前有两个查询分别产生我想要的结果：

这是两个查询：

SELECT contact_id FROM contacts 
WHERE acc_id = 1 AND email LIKE "paul%"

SELECT c0.contact_id 
FROM contact_tags c0 INNER JOIN contact_tags c1 
on c0.contact_id = c1.contact_id INNER JOIN contact_tags c2 
on c1.contact_id = c2.contact_id where c0.tag_id = 1 
AND c1.tag_id = 2 AND c2.tag_id = 3

这是表中的一些示例数据：

Contacts:

contact_id    acc_id     email
    54          1        [email protected]

Tags:

id     contact_id     tag_id 
1         54            1
2         54            2
3         54            3
4         50            1
5         50            2

两个查询在独立运行时都会产生正确的结果：

contact_id
    54

但是我试图在其中嵌套一个查询另一个从单个查询中产生相同的结果：

这是我尝试过的：

SELECT c0.contact_id 
FROM 
(
  SELECT contact_id 
   FROM contacts 
    WHERE acc_id = 1 AND email LIKE "paul%"
) AS c0 
LEFT JOIN contact_tags AS c1 
ON c1.contact_id = c0.contact_id 
AND (
  SELECT c0.contact_id FROM contact_tags c0 
  INNER JOIN contact_tags c1 
  on c0.contact_id = c1.contact_id 
  INNER JOIN contact_tags c2 on c1.contact_id = c2.contact_id 
  where c0.tag_id = 1 AND c1.tag_id = 2 AND c2.tag_id = 3
   ) 
 WHERE c1.id IS NOT NULL

但是我知道这是不对的，因为我只想返回与上述所有条件匹配的单个唯一联系人 ID：

contact_id
   54
   54
   54
   54

如果有人可以帮助我对此，我们将不胜感激。

谢谢

Answer 1

Select contact_id
From contacts
Where acc_id = 1 And email Like 'paul%'
    And contact_id In   (
                            Select Tags1.contact_id
                            From contact_tags As Tags1
                            Where Tags1.tag_id In(1,2,3)
                            Group By Tags1.contact_id
                            Having Count( Distinct Tags1.tag_id ) = 3
                            )

或者：

Select contact_id
From contacts
Where contact_id In (
                        Select C1.contact_id
                        From contact_tags As Tags1
                            Join contacts As C1
                                On C1.contact_id = Tags1.contact_id
                        Where Tags1.tag_id In(1,2,3)
                            And C1.acc_id = 1
                            And C1.email Like 'paul%'
                        Group By C1.contact_id
                        Having Count( Distinct Tags1.tag_id ) = 3
                        )

Answer 2

要让查询返回从第一个和第二个查询返回的所有联系人，请使用以下命令：（

假设第一个查询不返回重复的 contact_id ）

SELECT contact_id
FROM contacts 
WHERE acc_id = 1
  AND email LIKE "paul%"

  AND contact_id IN

  ( SELECT c0.contact_id 
    FROM contact_tags c0
      INNER JOIN contact_tags c1 
        ON c0.contact_id = c1.contact_id
      INNER JOIN contact_tags c2 
        ON c1.contact_id = c2.contact_id
    WHERE c0.tag_id = 1 
      AND c1.tag_id = 2
      AND c2.tag_id = 3
  )