Calculated Column performance

Hi,
Is calulation more efficent in the SQL CODE or in a Calculated Column? If
I'm correct the Calculated Column is done on the client SELECT query every
time where as my INSERT TSQL code will only do it once on the INSERT?
Thanks
DECLARE
@.ACCDCC_Table TABLE
(cnt INT NULL,
Time INT NULL,
Location FLOAT NULL,
FPM1 FLOAT NULL,
FPM2 FLOAT NULL,
FPM_Diff AS (
CASE
WHEN
FPM1 IS NULL OR
FPM2 IS NULL THEN NULL
ELSE
FPM2 - FPM1
END),
AccDcc VARCHAR(10) NULL
)
as per doing this:
UPDATE
@.ACCDCC_Table
SET
FPM_Diff = FPM2 - FPM1
WHERE
FPM_Diff IS NULL
--
don> Is calulation more efficent in the SQL CODE or in a Calculated Column? If
> I'm correct the Calculated Column is done on the client SELECT query every
> time where as my INSERT TSQL code will only do it once on the INSERT?
That's correct.
The flip side is that you will have to constantly maintain the value in the
"calculated" column if you're going to rely on doing it manually.
A|||Thanks
"AB - MVP" wrote:

> That's correct.
> The flip side is that you will have to constantly maintain the value in th
e
> "calculated" column if you're going to rely on doing it manually.
> A
>
>|||Think you meant you have to maintain it when you are doing it once, on
update. If it's calculated automatically, every time you "select" the
column, the value is not being stored in database, It's being re-calculated
every time you do a select, so there's no maintenance required.
Which is better depends on whether you need
A) Insert/Update Performance, and/Or storage Size Constraints -- Use
Calculated Column, or
B) Select Performance is the main concern -- Then Use persisted Column and
maintain it upon every Insert/Update
"AB - MVP" wrote:

> That's correct.
> The flip side is that you will have to constantly maintain the value in th
e
> "calculated" column if you're going to rely on doing it manually.
> A
>
>|||Thanks
"CBretana" wrote:
> Think you meant you have to maintain it when you are doing it once, on
> update. If it's calculated automatically, every time you "select" the
> column, the value is not being stored in database, It's being re-calculate
d
> every time you do a select, so there's no maintenance required.
> Which is better depends on whether you need
> A) Insert/Update Performance, and/Or storage Size Constraints -- Use
> Calculated Column, or
> B) Select Performance is the main concern -- Then Use persisted Column and
> maintain it upon every Insert/Update
> "AB - MVP" wrote:
>|||I guess someone missed the meaning of "quotes" around "calculated"... <sigh>
"donron" <donron@.discussions.microsoft.com> wrote in message
news:2CCDA1CD-B43E-4D0E-AEFF-6C77615F5755@.microsoft.com...
> Thanks
> "CBretana" wrote:
>|||that would be me... but rereading, (I may be just dense this am), but I'm
still not sure what you mean by it... I thought it was just a typo...
"AB - MVP" wrote:

> I guess someone missed the meaning of "quotes" around "calculated"... <sig
h>
>
>
> "donron" <donron@.discussions.microsoft.com> wrote in message
> news:2CCDA1CD-B43E-4D0E-AEFF-6C77615F5755@.microsoft.com...
>
>