NullIf() to Prevent Divide by Zero

Question

In my query, when calculating the average, I encounter a divide by zero error. I am attempting to resolve this by using Nullif, but I don't think my syntax is correct as Coldfusion throws an error stating incorrect syntax near ')'.

My query is:

<cfquery name="getValueAdd" datasource="#myDSN#">
    select d.partnum, sum(docunitprice * orderqty) as total_sales, 
    sum((c.avglaborcost + c.avgburdencost + c.avgmaterialcost + c.avgsubcontcost + c.avgmtlburcost)*d.orderqty) as total_cost,
    sum((docunitprice * orderqty)-((c.avglaborcost + c.avgburdencost + c.avgmaterialcost + c.avgsubcontcost + c.avgmtlburcost)*d.orderqty)) as Value_add,
   avg (isNull(
((((docunitprice * orderqty)-((c.avglaborcost + c.avgburdencost + c.avgmaterialcost + c.avgsubcontcost + c.avgmtlburcost)*d.orderqty))/ (nullIf(docunitprice * orderqty), 0),0)
))) as PercValueAdd
    from orderhed h with(nolock), orderdtl d with(nolock), partcost c with(nolock)
    where h.company = 'PC68300'
    and d.company = h.company
    and c.company = h.company
    and d.ordernum = h.ordernum
    and c.partnum = d.partnum
    and hdcasenum =  <cfqueryparam cfsqltype="cf_sql_integer" value="#rc.hdcasenum#" />   
    group by d.partnum
</cfquery>

Can anyone clarify the syntax for me please?

Answer 1

NullIf() takes two parameters. Did you search for the NullIf() documentation?

NULLIF returns the first expression if the two expressions are not equal. If the expressions are equal, NULLIF returns a null value of the type of the first expression.

Here is an example: http://www.bennadel.com/blog/984-Using-NULLIF-To-Prevent-Divide-By-Zero-Errors-In-SQL.htm