Sub-Query not Aggregating in Select

Question

I have this select statement:

SELECT p.WPD, count(b.PID) as ParcelsPerBlck, 
(SELECT count(PID) 
FROM bos05eb 
WHERE ptype BETWEEN 009 AND 133) as ResdOnly 
FROM ebos_parcels05 p, bos05eb b 
WHERE p.PID_LONG = b.PID
GROUP BY p.WPD;

I want the results of the sub-query in the select statement to also group by p.WPD. But I get the result of the query in each row as follows:

WPD           ParcelsPerBlck    ResdOnly
01-02-030     38                6198
01-08-035     56                6198    
01-04-060     11                6198

and so on.

Can the results of a sub-query not be grouped so that I only get the result count of the sub-query ResdOnly for each row?

Answer 1

You can use conditional aggregation for this without the need for a correlated subquery:

select 
    p.WPD, 
    count(b.PID) as ParcelsPerBlck, 
    sum(case when b.ptype between 009 AND 133 then 1 else 0 end) as ResdOnly 
from 
    ebos_parcels05 p
join 
    bos05eb b on p.PID_LONG = b.PID
group by 
    p.WPD

Please note the usage of the explicit join syntax -- no need to use commas in the from clause.