Question

I was wondering if anybody here could help with a problem I am having. I am trying to combine 2 mysql queries into one query using sub queries. I currently have the 2 queries separatly which produce the results i want:

Here are the 2 queries:

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

Here is some example data from the tables:

Contacts:

contact_id    acc_id     email
    54          1        [e-mail]

Tags:

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

Both queries when run independently produce this result which is correct:

contact_id
    54

However I am trying to nest one query inside the other to produce the same result from a single query:

Here is what I have tried:

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

However I know this is not right as i want to return just the single unique contact id which matches all conditions as above:

contact_id
   54
   54
   54
   54

If anyone could help me out with this it would be much appreciated.

Thanks

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
                            )

Or:

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
                        )