coalesce doesn't work when grouping is used - coldfusion

Question

I have an easy question. I'm trying to use coalesce in combination with a group by clause. I want to get 0 values when the variable is null. Here is my sql server code:
SELECT SUM(COALESCE(NETTOTAL,0)) AS NETTOTAL,DATEPART(MM,RECORD_DATE) MONTH
FROM ORDERS WHERE ORDER_EMPLOYEE_ID=#attributes.record_emp_id#
GROUP BY DATEPART(MM,RECORD_DATE) ORDER BY MONTH
.. and my output:
<tr height="20">
<td>Orders</td>
<cfoutput query="get_orders"><td style="text-align:center;">#tlformat(nettotal,2)# - #month#</td></cfoutput>
</tr>
This code is just for the orders. There is also the sales row. Anyway here is the screenshot to make it more clear:
http://i.stack.imgur.com/VIAmr.png
To make it more clear I added the number of the month. As you can see the order is broken since there are no zero values for the other months...
P.S.Thank you all for the help! i really appreciate it!

Answer 1

Your query is not at fault. You are trying to select from ORDERS based on each employee_id. You are then looping over it.
If a given month has no orders, then there will be no row for it within the result set.
Even if there were only orders for the last 4 months, they would get pushed to the first 4 as you are not checking that the month you are currently outputting matches the column header.
For a bit of metacode, I would go down this route
1 - create an array as follows
arrMonths= [
{orders=0,sales=0},
{orders=0,sales=0}....
]
This will give you a stc you can iterate over later.
2 - I would then loop over each query
<cfoutput query="get_orders">
<cfset arrMonths[month].orders = nettotal>
</cfoutput>
3 - I would then iterate over the array
<tr height="20">
<td>Orders</td>
<cfoutput from="1" to="#ArrayLen(arrMonths)#" index="thisMonth">
<td style="text-align:center;">#tlformat(arrMonths[thisMonth].orders,2)# - #thisMonth#</td>
</cfoutput>
</tr>
This way, every month will ALWAYS have a value even if it's 0. You can also ditch the coalesce as the simple fact that rows with no orders have no records means they default to 0 so your query may become
SELECT
SUM(COALESCE(NETTOTAL)) AS NETTOTAL,
DATEPART(MM,RECORD_DATE) MONTH
FROM ORDERS
WHERE ORDER_EMPLOYEE_ID=<cfqueryparam cfsqltype="cf_sql_integer" value="#attributes.record_emp_id#">
GROUP BY DATEPART(MM,RECORD_DATE)
MONTH is now not necessary as it's just inserting into the array which deals with ordering

Answer 2

TRy ISNULL() Instead of COALESCE .
COALESCE is used for multiple argumentsif multiple arguments are not needed you could use ISNULL

Answer 3

Try to invert the order of the functions Sum and Coalesce.
IsNull might be more readable as well:
SELECT IsNull(SUM(NETTOTAL), 0) AS NETTOTAL,
DATEPART(MM, RECORD_DATE) MONTH
FROM ORDERS
WHERE ORDER_EMPLOYEE_ID = #attributes.record_emp_id#
GROUP BY DATEPART(MM, RECORD_DATE)
ORDER BY MONTH
If there are no elements of NETTOTAL, Coalesce from your code would not be called. So a Sum of no rows will be null.