Conditional AND statement based on results of COUNT() - sql

Question

I'm getting lost in a query's logic, and I need some help. To start, I have a parent table Campaigns. Then, a child table CampaignParks that looks like this:
select * from CampaignParks
For business reasons I won't bore you with, we need to include Parks in the Campaign table even if they are not included in the Campaign. To actually include them in the campaign, there is a flag for that. None, one, or multiple Parks might be set to Include In Campaign.
Ok. Simple enough. Now...
Given a #ParkID, I need to return all parent Campaigns where the ParkID is a match, but ONLY if one (or more) of the IncludeInCampaign flags for the campaign has been set. If no IncludeInCampaign flags for a given campaign have been set, then we just ignore the value of #Parks. We don't care about it.
Examples:
#ParkID = 11070. We get back 4 & 1
#ParkID = 11526. We get back 1
#ParkID = 26496. We get back 1
#ParkID = null. We get back 4 & 1
ParkID = 69. We get back 1.
So, I think the query would look something like this:
SELECT
DISTINCT
sc.ContactID,
cp.*
FROM
Campaigns sc
JOIN CampaignParks cp on sc.CampaignID = cp.CampaignID
WHERE
((SELECT COUNT(*) FROM CampaignParks cp2 WHERE cp2.CampaignID = sc.CampaignID AND cp2.IncludeInCampaign = 1) > 0 OR cp.ParkID = #ParkID)
But, this isn't getting me the right results.
(I need to take my daughter to gymnastics... I'll take a look at relies when I get back. Thank you!!)

Answer 1

I think your code is close. The major difference is the AND versus OR in the WHERE clause:
SELECT sc.ContactID, cp.*
FROM Campaigns c JOIN
CampaignParks cp
on sc.CampaignID = cp.CampaignID
WHERE cp.ParkId = #ParkId AND
EXISTS (SELECT 1
FROM CampaignParks cp2
WHERE cp2.CampaignID = cp.CampaignID AND
cp2.IncludeInCampaign = 1
);