Query with Union of two Synchronized Data Extensions

Question

I have a query using a Union to combine two Queries. In the Query editor I run into no errors but when I click finish, I get the error Cannot find table 0. So syntax errors show up so I am lost.

Here is my query

    -- Query 1: Contact_Salesforce
SELECT 
    D.Email AS EmailAddress,
    D.Id AS Id,
    D.FirstName AS FirstName,
    D.LastName AS LastName
FROM 
    Contact_Salesforce D
WHERE 
    D.Spotlight__c = 1 
    AND D.Email IS NOT NULL 
    AND D.Email != ''

UNION

-- Query 2: CampaignMember_Salesforce
SELECT 
    G.Email AS EmailAddress,
    G.LeadOrContactId AS Id,
    NULL AS FirstName, -- Ensure columns match with Query 1
    NULL AS LastName   -- Ensure columns match with Query 1
FROM 
    CampaignMember_Salesforce G
WHERE 
    G.Email IS NOT NULL 
    AND G.Email != ''
    AND G.LeadOrContactId IS NOT NULL
    AND G.LeadOrContactId != ''

Answer 1

I resolved the issue. It didn't like my use of comments in the query. All Good now!