Divide Zero error when calculating Sales % in SQL - sql

Question

I keep getting the following error message:
Msg 8134, Level 16, State 1, Line 1 Divide by zero error encountered.
I've seen some posts about using IFNULL which I have tried.
For example:
,Case when a.DiscountReasonCode = 'RL' then IFNULL(((a.ORIGINALRETAIL-a.RetOne) / (a.ORIGINALRETAIL) * 100),0) end as [PctSB]
But this returns the following error:
'IFNULL' is not a recognized built-in function name.
What I'm doing is trying to calculate the proper sales percent and then find and compare it to what is already in the table to find errors or missing Sales %'s.
I'm not sure where I'm going wrong but any help would be greatly appreciated.
SELECT
a.packnum
,a.description
,a.CatID
,a.PctSavings
,Case when a.DiscountReasonCode = 'RL' then (a.ORIGINALRETAIL-a.RetOne) / (a.ORIGINALRETAIL) * 100
end as [PctSB]
FROM PIC704Current a Join CatalogInfo b ON (a.CatID = b.Catalog) and (a.Year = b.MailYear)
WHERE
b.MediaId in('CAT Catalog','SCAT Sale Catalog','SSTF Sale Statement Stuff','STUF Statement
Stuffer','PKG Package Insert','SPKG Sale Pkg Insert')
and a.DiscountReasonCode = 'RL'
and a.year >='2020'
and (Case when a.PctSavings <> (a.ORIGINALRETAIL-a.RetOne)/a.ORIGINALRETAIL*100 then 'False' else
'True' END) = 'False'
Thanks

Answer 1

Wrapping a divide in a null test will not get rid of the divide by 0 error. Instead, you need to check whether the value being divided by is 0 and return a different value instead. You can do this using IIF:
IIF(a.ORIGINALRETAIL = 0, 0, 100.0 * (a.ORIGINALRETAIL-a.RetOne) / a.ORIGINALRETAIL)

Answer 2

You can use coalesce or isnull . MySQL uses ifnull
case
when a.DiscountReasonCode = 'RL' then (a.ORIGINALRETAIL-a.RetOne) /
NULLIF(a.ORIGINALRETAIL, 0) * 100
end as [PctSB]

Answer 3

Msg 8134, Level 16, State 1, Line 1 Divide by zero error encountered.
This error suggests that your denominator is 0 so you can change it to NULL using a case expression.
'IFNULL' is not a recognized built-in function name.
In SQL Server , you can use ISNULL or Coalesce
CASE WHEN a.DiscountReasonCode = 'RL'
THEN ISNULL(((a.ORIGINALRETAIL-a.RetOne)/(CASE WHEN a.ORIGINALRETAIL = 0
THEN NULL
ELSE a.ORIGINALRETAIL
END) * 100),0)
END AS [PctSB]

Answer 4

I think the posts you've seen mentioning IFNULL might actually have been mentioning NULLIF, you just remembered it the wrong way round. One of the typical tricks to avoid a DIV/0 error in sqlserver:
some_number / NULLIF(other_number_maybe_zero, 0)
If the divisor is 0, it is converted to null, meaning the result is null rather than an error
In standard SQL you can do it too:
some_number / CASE WHEN other_number_maybe_zero = 0 THEN NULL ELSE other_number_maybe_zero END
It's just a bit more wordy

Answer 5

The logic that you want is provided by NULLIF():
(a.ORIGINALRETAIL - a.RetOne) * 100.0 / NULLIF(a.ORIGINALRETAIL, 0)) * 100) as [PctSB]
Using the standard SQL function NULLIF() is the simplest way to do what you want, and I recommend that you write the logic this way. It replaces any 0 value with NULL -- thereby avoiding the divide-by-zero.