Question

A) When goods are sold, a table will record an “O” in column ID & a “N” in column TYPE:-

SKU      ID  TYPE  NR
-------------------------
HAB1122  O   N     201211

B) When goods are returned, a table will record an “O” in column ID & a “R” in column TYPE:-

SKU      ID  TYPE  NR
-------------------------
HAB1122  O   R     201223

Scenario 1

Goods were sold & returned later. It was sold subsequently:-

SKU      ID  TYPE  NR
-------------------------
HAB1122  O   N     201211
HAB1122  O   R     201223
HAB1122  O   N     201245
HAB2233  O   N     201263
HAB3344  O   N     201303
HAB3344  O   R     201341

Using SQL:-

Select SKU, max(NR) 
from tableA
where SKU like ‘HAB%’ and ID = ‘O’
group by SKU

Results:-

SKU       NR
----------------
HAB1122   201245
HAB2233   201263
HAB3344   201341

This is the correct result as I wish to track down the last NR of the goods sold whether the goods are sold or returned.

If I wish to track down the last NR of goods with status sold only, the expected results should be:-

SKU      NR
---------------
HAB1122  201245
HAB2233  201263

HAB3344 is not considered as the goods are returned & not sold subsequently.

How should I change the SQL?

Answer 1

Try this:

select   SKU, max(NR)
from     TABLEA T1
where    SKU like 'HAB%' and ID = 'O'
group by SKU
having   max(NR) <> (select nvl(max(NR), 0)
                     from   TABLEA T2
                     where  T1.SKU = T2.SKU and T2.type = 'R');

This is using Oracle. You didn’t indicate your system so the having may not work specifically on yours but an equivalent will.