how to use is null with case statements - sql

Question

Hi can any one say me how to write query in sql server management studio for statement =>if(isnull("GROSS_SF")=1 or "GROSS_SF"=0,0,"GROSS_SALES"/"GROSS_SF")
by using case statement :
CASE
WHEN ("GROSS_SF"=1 or "GROSS_SF"=0) isnull then 0
else "GROSS_SALES"/"GROSS_SF"
end/* i am getting error if i write it like this */
thanks in advance

Answer 1

If you want to avoid a divide by zero, while at the same time also handling NULL, then you may try the following logic:
CASE WHEN COALESCE(GROSS_SF, 0) = 0
THEN 0
ELSE GROSS_SALES / GROSS_SF END AS output
To be clear, the above logic would return a zero value should either the GROSS_SF be zero or NULL.

Answer 2

I think what are you looking for is IFNULL, look here https://www.w3schools.com/sql/sql_isnull.asp

Answer 3

You are close. You can do:
(CASE WHEN "GROSS_SF" IS NULL OR "GROSS_SF" = 0 THEN 0
ELSE "GROSS_SALES" / "GROSS_SF"
END)
In SQL, divide by zero errors are often avoided using NULLIF():
"GROSS_SALES" / NULLIF("GROSS_SF", 0)
However, that returns NULL rather than 0. If you really want zero:
COALESCE("GROSS_SALES" / NULLIF("GROSS_SF", 0), 0)
This is a bit shorter to write and almost equivalent to your version (this returns 0 if "GROSS_SALES" is NULL, which your version does not).

Answer 4

You can use NULLIF() to prevent arithmetic divide by zero errors :
select . . . ,
GROSS_SALES / nullif(GROSS_SF, 0)
from table t;
However, this would return null instead of error, if you want to display 0 instead then you need to use isnull() (MS SQL Specific) or coalesce() (SQL Standard).
So, you can express it :
select . . . ,
isnull(GROSS_SALES / nullif(GROSS_SF, 0), 0)
from table t;