SQL group function nested too deeply

问题

I want to make a SQL query which finds the pname of parts which are the least repeated in supplier_parts_shipment.

Table 1 supplier (sno, sname, city)

1, ahmad, jeddah
2,kaled,med
3,njwa,med

Table 2 parts (pno, pname, color)

1, laptop, red
2,keybord,blue

Table 3 supplier_parts_shipment (shno, sno, pno, date)

1,1,1,2014
2,2,1,2014
3,3,2,2014

I tried something like this:

  SELECT pname 
       , min(count(pno)) 
    FROM parts 
   WHERE pno IN (SELECT pno 
                   FROM supplier_parts_shipment 
                  group by 
                        pname 
                 HAVING min(count(pno))
                )
SQL> /
pno IN(SELECT pno FROM supplier_parts_shipment group by pname HAVING min(count(pno))))
                                                                         *
ERROR at line 2:
ORA-00935: group function is nested too deeply

回答1:

I would have gone about it in a different manner.

First create a query that shows the counts of shipments by pname ordered in ascending values. Use that as a subquery and pick the first.

SELECT * FROM (
    SELECT COUNT(sps.pno), p.pname 
    FROM supplier_parts_shipment sps
    JOIN parts p on sps.pno = p.pno
    GROUP BY pname
    ORDER BY COUNT(sps.pno) ASC)
WHERE ROWNUM = 1

回答2:

If there are multiple parts which are least frequent and you want all of them then:

WITH pno_frequencies AS (
  SELECT pno,
         COUNT(1) AS pno_cnt
  FROM   supplier_parts_shipment
  GROUP BY pno
),
least_frequent_pnos AS (
  SELECT pno
  FROM   pno_frequencies
  WHERE  pno_cnt = ( SELECT MIN( pno_cnt ) FROM pno_frequencies )
)
SELECT pname
FROM   parts p
WHERE  EXISTS (SELECT 1
               FROM   least_frequent_pnos f
               WHERE  p.pno = f.pno
              );

If you only want a single part regardless of whether there are multiple parts with the same minimum frequency then:

WITH pno_frequencies AS (
  SELECT pno,
         COUNT(1) AS pno_cnt
  FROM   supplier_parts_shipment
  GROUP BY pno
  ORDER BY pno_cnt ASC
),
least_frequent_pno AS (
  SELECT pno
  FROM   pno_frequencies
  WHERE  ROWNUM = 1
)
SELECT pname
FROM   parts p
WHERE  EXISTS (SELECT 1
               FROM   least_frequent_pno f
               WHERE  p.pno = f.pno
              );

SQLFIDDLE

回答3:

min(count(pno))

makes no sense. that is why you are getting the error. try:

select parts.pname
     , subse.c 
  from (select pno
             , dense_rank() over (order by c asc) r
             , c
          from (select pno
                     , count(pno) as c
                  from supplier_parts_shipment
                 group by
                       pno
               )
       ) subse
 inner join parts
    on (parts.pno = subse.pno)
 where subse.r = 1

the innermost select counts the supplier_parts_shipment for pno, the second level finds the pno that has the least count from the innermost. the outermost select then joins pname from parts and filters to the one that has the least repeats.

来源：https://stackoverflow.com/questions/20035212/sql-group-function-nested-too-deeply

标签

sql

Oracle

aggregate-functions