Debugging SQL Query - sql

Question

So I've researched this question but the solutions I've found are for debugging syntax errors, whereas I am encountering logic errors. I have a query in Access that is joining a table to a query, and the query is working almost perfectly. It runs, it's displaying exactly what I want where I want it to. The only problem is that the data it is showing is wrong. It has a group by field, and then the other fields are sums of fields based on the query joins. However the sums are wrong for some groupbys and right for others, and I'm unsure why. Is there a way to get into my code and see where some of these queries are grabbing the numbers?
Here is query I'm working with:
SELECT m.Bldg, Sum([e].[TotCost]*IIf([e].[Utility]="E",1,0)) AS ECost, Sum(g.TotCost*Switch(g.Utility='G',1,True,0)) AS GCost, Sum(h.TotCost*Switch(h.Utility='H',1,True,0)) AS HCost, Sum(c.TotCost*Switch(c.Utility='C',1,True,0)) AS CCost, Sum(w.TotCost*Switch(w.Utility='W',1,True,0)) AS WCost, Sum(s.TotCost*Switch(s.Utility='S',1,True,0)) AS SCost
FROM (((((tblBldgMeters AS m LEFT JOIN qryCurrentMonthMtrHis AS e ON m.EMeters = e.MeterID) LEFT JOIN qryCurrentMonthMtrHis AS g ON m.GMeters = g.MeterID) LEFT JOIN qryCurrentMonthMtrHis AS h ON m.HMeters = h.MeterID) LEFT JOIN qryCurrentMonthMtrHis AS c ON m.CMeters = c.MeterID) LEFT JOIN qryCurrentMonthMtrHis AS w ON m.WMeters = w.MeterID) LEFT JOIN qryCurrentMonthMtrHis AS s ON m.SMeters = s.MeterID
GROUP BY m.Bldg;
The problem is that the Cost fields will sometimes be right and sometimes be wrong, and I can't understand why. It can be anywhere from a hundred to a million dollars off. Each building has several meters that have separate costs that have to be added together, and so I have a query with just the current months costs for each meter, and then a table that lists all the buildings and the corresponding meters with it.

Answer 1

The best approach is to isolate a data set that works and one that doesn't . Then break the aggregate and verify the data. See what the query is actually doing... Without data samples or even a copy of access I could shoot from the hip with something like:
SELECT m.Bldg,
[e].[TotCost]*IIf([e].[Utility]="E",1,0) AS ECost,
e.Utility as e_Utility
g.TotCost*Switch(g.Utility='G',1,True,0) AS GCost,
g.Utility as g_Utility,
h.TotCost*Switch(h.Utility='H',1,True,0) AS HCost,
h.Utility as h_Utility,
c.TotCost*Switch(c.Utility='C',1,True,0) AS CCost,
c.utility as c_Utility,
w.TotCost*Switch(w.Utility='W',1,True,0) AS WCost,
w.Utility as w_Utility
s.TotCost*Switch(s.Utility='S',1,True,0) AS SCost
s.Utility as s_Utility
FROM
(((((tblBldgMeters AS m
LEFT JOIN qryCurrentMonthMtrHis AS e ON m.EMeters = e.MeterID)
LEFT JOIN qryCurrentMonthMtrHis AS g ON m.GMeters = g.MeterID)
LEFT JOIN qryCurrentMonthMtrHis AS h ON m.HMeters = h.MeterID)
LEFT JOIN qryCurrentMonthMtrHis AS c ON m.CMeters = c.MeterID)
LEFT JOIN qryCurrentMonthMtrHis AS w ON m.WMeters = w.MeterID)
LEFT JOIN qryCurrentMonthMtrHis AS s ON m.SMeters = s.MeterID
You might want to separate out the TotCost fields as well. This should give you decent insight into what is actually happening in the query. That's always my go to in troubleshooting though... Break the aggregate, check the data. If the data set is to large, isolate a test group and narrow it down.