Computed Column Divide by Zero?

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Computed Column Divide by Zero?

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deepak.a SSCertifiable Points: 5330 More actions · Answer 1

Hugo Kornelis (10/15/2010)
deepak.a (10/15/2010)
Hugo Kornelis (10/15/2010)
deepak.a (10/15/2010)
one more doubt on creating the index on computed columns
(...)
in the above Quesries second one (Query 2) thrown on error while creating the index on computed column but the Query 1 and Query 3 not thrown error i'm confused about this
As implied by the text of the error message, a computed column that SQL Server considers imprecise can not be indexed without first pesisting it. But a computed column that is not imprecies can be persisted.
All results of calculations with floating point data is considered imprecise, that's the reason you get the error in query 2.
thanks for your reply hugo , but in query 3 i have used decimal (decimal(18,2))data type for that there s no error thrown
That's because decimal(18,2) is NOT imprecise, whereas float is.

Thanks a Lot hugo for the reply

tilew-948340 Hall of Fame Points: 3431 More actions · Answer 2

Hugo Kornelis (10/15/2010)
tilew-948340 (10/15/2010)
Hi Hugo.
The first time I tried the PERSISTED, I got the divide by zero error AFTER the "show table" wich does not seem to be, as I understand it, what it should be doing. So I tried many "set" option, wich brought me to the "declare" error...
So, if I put the PERSISTED word, should not the error happend after the "Insert null"?
Here is the code that I used - if you compare this to the QotD, you'll see that adding PERSISTED at one place is the only modification.
...
If I run this (from SSMS, against SQL Server 2005), I get an error after "Insert Zeroes", and a result set with two rows (one with values; one with NULLs)

ah! HA! I knew I was doing someting wrong. I was putting the "PERSISTED" after the "QTot AS QF1 + QF2", wich mean nothing for a division by zero. Now, I do understand what "persisted" do!

Thank you very much!

SQLRNNR SSC Guru Points: 281334 More actions · Answer 3

Thanks for the question.

Jason...AKA CirqueDeSQLeil
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SQLWinther SSCertifiable Points: 6294 More actions · Answer 4

Good question, i thought it would happen upon insert, but I didn't realize that it was not persisted.

/Håkan Winther
MCITP:Database Developer 2008
MCTS: SQL Server 2008, Implementation and Maintenance
MCSE: Data Platform