SQL Statement -- Throws GROUP BY issue on NVL

Question

Hey All,
This is pretty much my first time tackling a very complex SQL Statement but the boss is adamant about it.
Anyways here is the information. I have 3 Tables. Table one Contains Work Order Infromation that will be listed or grouped. Table 2 and Table 3 house information that needs to be summed (Estimate hours and Actual Hours).
So my SQL Statement looked something like this... (Its a mess)
select workorder.wolo3, workorder.wojp1, workorder.wonum, workorder.description, workorder.location, workorder.status, workorder.wopriority, workorder.targstartdate, workorder.reportdate, workorder.pmnum, workorder.schedstart, sum(labtrans.regularhrs + labtrans.premiumpayhours) as actualhours, sum(wplabor.quantity * wplabor.laborhrs) as estimatehrs
from maximo.workorder left outer join maximo.labtrans on labtrans.regularhrs > 0 and labtrans.refwo = workorder.wonum and labtrans.siteid = workorder.siteid or labtrans.premiumpayratetype = 'MULTIPLIER' and labtrans.refwo = workorder.wonum and labtrans.siteid = workorder.siteid left outer join maximo.wplabor on wplabor.wonum = workorder.wonum and wplabor.siteid = workorder.siteid
where workorder.istask=0 and workorder.siteid='NTS' and workorder.status in ('INPRG','SCHED') and workorder.crewid in ('MAINT','DAF') and workorder.schedstart <= TO_DATE('12-13-2009','MM-DD-YYYY') and wolo3 is not null group by workorder.wonum, workorder.status, workorder.wopriority, workorder.pmnum, workorder.location, workorder.description, workorder.targstartdate, workorder.reportdate, workorder.schedstart, workorder.wolo3, workorder.wojp1
Now the problem is that the 2nd sum (Estimate Hrs) gets HUGE numbers if there are multiple rows in Actual Hours. So I did some searching. Seems that if I used the NVL function in the SQL Statement it would fix the issue...
select workorder.wolo3, workorder.wojp1, workorder.wonum, workorder.description, workorder.location, workorder.status, workorder.wopriority, workorder.targstartdate, workorder.reportdate, workorder.pmnum, workorder.schedstart, sum(labtrans.regularhrs + labtrans.premiumpayhours) as actualhours,
nvl((select sum(wplabor.quantity * wplabor.laborhrs) from maximo.wplabor where wplabor.wonum = workorder.wonum and wplabor.siteid = workorder.siteid),0)
from maximo.workorder left outer join maximo.labtrans on labtrans.regularhrs > 0 and labtrans.refwo = workorder.wonum and
labtrans.siteid = workorder.siteid or labtrans.premiumpayratetype = 'MULTIPLIER' and labtrans.refwo = workorder.wonum and
labtrans.siteid = workorder.siteid
where workorder.istask=0 and workorder.siteid='NTS' and workorder.status in ('INPRG','SCHED') and
workorder.crewid in ('MAINT','DAF') and workorder.schedstart <= TO_DATE('12-13-2009','MM-DD-YYYY') and wolo3 is not null
group by workorder.wonum, workorder.status, workorder.wopriority, workorder.pmnum, workorder.location, workorder.description, workorder.targstartdate, workorder.reportdate, workorder.schedstart, workorder.wolo3, workorder.wojp1
However If get the error not a GROUP BY expression.
I really need this to work. How can I get the NVL to work with out having to define a Group for it. The problem is that it is a "alias column" and you cannot Group by those fields. Frustation sets in... UGH!
Thanks in Advance, Ben.

Answer 1

Hi, Ben,
Wlecome to the forum!
user12273726 wrote:
So my SQL Statement looked something like this... (Its a mess)You're right. Fix that first.
Put each SELECT item, each condition, and each GROUP BY expression on a separate line. Indent to show here the clauses (SELECT, FROM, WHERE) are.
For example:
SELECT    workorder.wolo3
,       workorder.wojp1
,       workorder.wonum
,       workorder.description
,       workorder.location
,       workorder.status
,       workorder.wopriority
,       workorder.targstartdate
,       workorder.reportdate
,       workorder.pmnum
,       workorder.schedstart
,       SUM (labtrans.regularhrs + labtrans.premiumpayhours)     AS actualhours
,       SUM (wplabor.quantity * wplabor.laborhrs)          AS estimatehrs
FROM                  maximo.workorder
LEFT OUTER JOIN   maximo.labtrans     ON      labtrans.regularhrs         > 0
                                   AND     labtrans.refwo              = workorder.wonum
                         AND     labtrans.siteid              = workorder.siteid
                         OR     labtrans.premiumpayratetype = 'MULTIPLIER'     -- WARNING!  Don't mix AND and OR
                         AND     labtrans.refwo              = workorder.wonum
                         AND     labtrans.siteid              = workorder.siteid
LEFT OUTER JOIN   maximo.wplabor     ON     wplabor.wonum              = workorder.wonum
                                   AND     wplabor.siteid              = workorder.siteid
WHERE     workorder.istask      = 0
AND       workorder.siteid       = 'NTS'
AND       workorder.status       IN ('INPRG','SCHED')
AND       workorder.crewid       IN ('MAINT','DAF')
AND       workorder.schedstart   <= TO_DATE ('12-13-2009','MM-DD-YYYY')
AND       wolo3                       IS NOT NULL
GROUP BY  workorder.wonum
,            workorder.status
,       workorder.wopriority
,       workorder.pmnum
,       workorder.location
,       workorder.description
,       workorder.targstartdate
,       workorder.reportdate
,       workorder.schedstart
,       workorder.wolo3
,       workorder.wojp1
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Now the problem is that the 2nd sum (Estimate Hrs) gets HUGE numbers if there are multiple rows in Actual Hours. Huge numbers are not necessarily wrong. Do yo mean the numbers computed by your query are much bigger than they are supposed to be?
So I did some searching. Seems that if I used the NVL function in the SQL Statement it would fix the issue...
select workorder.wolo3, workorder.wojp1, workorder.wonum, workorder.description, workorder.location, workorder.status, workorder.wopriority, workorder.targstartdate, workorder.reportdate, workorder.pmnum, workorder.schedstart, sum(labtrans.regularhrs + labtrans.premiumpayhours) as actualhours,
nvl((select sum(wplabor.quantity * wplabor.laborhrs) from maximo.wplabor where wplabor.wonum = workorder.wonum and wplabor.siteid = workorder.siteid),0)
...It looks like you have a Chasm Trap, where you have multiple, independent one-to-many relationships on the same table, and the solution to aggregate them in separate queruies.
It looks like you're trying to aggregate wplabor in scalar sub-queries, which makes the GROUP BY more complicated (as you discovered), and is also very inefficient.
It would be easier to code and more efficient to run if you aggregated wplabor in a sub-query, and then joined to this sub-query (and not the actual wplabor table) in your main query.
If you'd like help, post a little sample data (CREATE TABLE and INSERT statements) for all three tables, and the results you want from that data.
Simplify as much as possible. Instead of GROUPing BY 11 columns, just GROUP BY, say, 3 columns: the 2 involved in the join condidiotns, and one more. Once you understand how to do this, adding the other expressions will be trivial.
You can also simplify by ignoring, for now, the WHERE clause, and, therefore, the columns involved in the WHERE clause. It looks like that has nothing to do with the problem. Again, adding the conditions later will be trivial.