SQL Server : divide by zero error - sql-server

Question

I have searched the forums and found several responses on this topic but as I am new to SQL I'm not getting it.
I created a TSQL query that when run returns "Divide by zero error". This is because I am dividing one column by another and there is a zero in one of the records. Ok, I got that part but I can't make heads or tails of the posts explaining how to resolve the issue.
SELECT
f.Sales_Rep1 AS 'Sales Rep'
, SUM(CAST(f.Other1_Revenue + f.Other2_Revenue AS FLOAT)) AS 'MRR'
, CW.MRR_Goal AS 'MRR Goal'
, SUM((f.Other1_Revenue + f.Other2_Revenue)/(CW.MRR_Goal)) AS 'Total'
, SUM(CAST(f.Product_Revenue + f.Service_Revenue AS FLOAT)) AS 'NRR'
, CW.NRR_Goal AS 'NRR Goal'
, (cw.MRR_Goal + cw.NRR_Goal)AS 'Total Goal'
FROM
dbo.v_rpt_Opportunity AS f
INNER JOIN
dbo.v_memberpickerlist AS m ON f.Sales_Rep1 = m.Member_ID
INNER JOIN
dbo.CW_SalesGoals AS CW ON CW.Sales_Rep = f.Sales_Rep1
WHERE
(f.Expected_Close_Date >= DATEADD(MM, DATEDIFF(MM, 0, GETDATE()), 0))
AND (m.activestatus = 'active') AND (f.Status = 'Won')
OR (f.Expected_Close_Date >= DATEADD(MM, DATEDIFF(MM, 0, GETDATE()), 0))
AND (m.activestatus = 'active')
AND (f.Status LIKE '%submitted%')
GROUP BY
f.Sales_Rep1, CW.MRR_Goal, CW.NRR_Goal,
f.Other1_Revenue, f.Other2_Revenue
I know the line that is causing the issue, but I do not know how to resolve it...
SUM((f.Other1_Revenue + f.Other2_Revenue) / (CW.MRR_Goal)) AS 'Total'
What I am trying to do is get the percentage of the goal but I cant get past the division to do that.
Any help would be greatly appreciated. Thank you!

Answer 1

You can use the nullif() function to avoid divide by zero exceptions:
(f.Other1_Revenue + f.Other2_Revenue) / nullif(CW.MRR_Goal, 0)
In the event that CW.MRR_Goal is 0, the result for the entire expression will be null1.
Sample:
select 1 / nullif(0, 0) -- null
1 I've selected null because, in my opinion, it's the most appropriate analogue for undefined in SQL. While that's helpful for an individual expression, it may not be what you're looking for in an aggregate sense.

Answer 2

Use a CASE statement:
SUM(CASE WHEN CW.MRR_Goal <> 0 THEN (f.Other1_Revenue + f.Other2_Revenue)/(CW.MRR_Goal) ELSE 0 END) AS 'Total'
This way, it will perform the division only if the value of CW.MRR_Goal in that record is other than zero; if it's zero, it will return 0

Answer 3

You could use an IIF:
SUM(IIF(CW.MRR_Goal = 0, 0, (f.Other1_Revenue + f.Other2_Revenue) / (CW.MRR_Goal))
This way if the goal is equal to 0 then it will SUM the 0 rather than trying the division whereas if the goal is not equal to 0 then it will do the division.
More on IIF https://msdn.microsoft.com/en-GB/library/hh213574.aspx
As user3540365 mentioned IIF only applies from SQL Server 2012 as opposed to CASE which applies from SQL Server 2008 onwards see here and is an SQL standard.