Q:

Combine Three Count Queries to One Result

I am learning as I go, but I have reached the limit to my self growth. I am looking to have the three queries below, display in one query. But I am lost in the terminology of joins and unions.
SELECT    DID.display as "DisplayID",
          COUNT(AltID.REFID) as "C_AltIDs"
FROM      DID,
          AltID
WHERE     DID.REFID = AltID.REFID
GROUP BY  AltID.REFID, DID.display 
ORDER BY  COUNT(AltID.REFID) desc;

SELECT    DID.display as "DisplayID",
          COUNT(address.REFID) as "C_AltAddresses"
FROM      DID,
          address
WHERE     DID.REFID = address.REFID
GROUP BY  address.REFID, DID.display 
ORDER BY  COUNT(address.REFID) desc;

SELECT    DID.display as "DisplayID",
          COUNT(name.REFID) as "C_AltNames"
FROM      DID,
          name
WHERE     DID.REFID = name.REFID
GROUP BY  name.REFID, DID.display 
ORDER BY  COUNT(name.REFID) desc;

**Desired end result**
|DisplayID|AltIDs|AltAddresses|AltNames|
    01       32        32         2
    02        2        12         4

A:

Maybe using correlated subqueries could work for you?
SELECT    
  DID.display as "DisplayID",
  (SELECT COUNT(AltID.REFID) FROM AltID WHERE REFID = DID.REFID) as "C_AltIDs",
  (SELECT COUNT(address.REFID) FROM address WHERE REFID = DID.REFID) as "C_AltAddresses",
  (SELECT COUNT(name.REFID) FROM name WHERE REFID = DID.REFID) as "C_AltNames" 
FROM DID
ORDER BY display 

Edit: an additional solution asked for in a comment:
;WITH x AS (
  SELECT    
    DID.display as "DisplayID",
    (SELECT COUNT(AltID.REFID) FROM AltID WHERE REFID = DID.REFID) as "C_AltIDs",
    (SELECT COUNT(address.REFID) FROM address WHERE REFID = DID.REFID) as "C_AltAddresses",
    (SELECT COUNT(name.REFID) FROM name WHERE REFID = DID.REFID) as "C_AltNames" 
  FROM DID
) 

SELECT *, C_AltIDs+C_AltAddresses+C_AltNames AS SumOfCounts 
FROM x

