Dynamic query in a function

Greetings:
I am trying to write a view that includes a column derived from a function
call.
The function is written thus:
CREATE FUNCTION dbo.fnc_CapArrayValue
(@.MEASUREMENTID INT,@.TRACKINGID BIGINT,@.JET INT)
RETURNS REAL
AS
BEGIN
Declare @.Result REAL
SET @.RESULT = (select @.JET from dbo.vw_CapArrayData where (measurement_id =
@.measurementid) and (tracking_id = @.trackingid))
RETURN @.Result
END
GO
What am I doing wrong here? When I run the view this function resides in, I
get a timeout error.Does the same query executed against the view return results in a resonable
time?
If not then posting the view definition and the definitions and indexes of
the underlying tables would give a few clues.
Is this an extract of somethimg much more complicated - if not I cannot see
much reason for using the function - unless you need it in a constraint or
similar.
Re-reading your post - is the function being used in a view definition, and
itself retriving data from a view (assuming vw_CapArrayData is a view?)
BTW you may get a deluge saying prefixing vw on the front of view names is a
bad idea, which I happen to think it is - be warned.
I suspect that the combination of a view based on a function, based on a
view has caused the optimiser to get a tad and produce a poor
execution plan.
Mike John
"Thomas Mick" <nospam@.nospam.com> wrote in message
news:y2ikg.3677$Oh1.923@.news01.roc.ny...
> Greetings:
> I am trying to write a view that includes a column derived from a function
> call.
> The function is written thus:
> CREATE FUNCTION dbo.fnc_CapArrayValue
> (@.MEASUREMENTID INT,@.TRACKINGID BIGINT,@.JET INT)
> RETURNS REAL
> AS
> BEGIN
> Declare @.Result REAL
> SET @.RESULT = (select @.JET from dbo.vw_CapArrayData where (measurement_id
> =
> @.measurementid) and (tracking_id = @.trackingid))
> RETURN @.Result
> END
> GO
> What am I doing wrong here? When I run the view this function resides in,
> I
> get a timeout error.
>|||You cannot use Dynamic SQL inside functions. The workaround is to use a CASE
expression like:
SET @.r = ( SELECT CASE @.p WHEN 'value_1' THEN col_1
WHEN 'value_2' THEN col_2
..
WHEN 'value_n' THEN col_n
END
FROM dbo.vw_CapArrayData
WHERE measurement_id = @.m_id
AND tracking_id = @.t_id ) ;
Alternatively you can create a procedure to get this information, however
you'll have to make careful considerations for security and performance.
Anith|||Thomas Mick (nospam@.nospam.com) writes:
> I am trying to write a view that includes a column derived from a function
> call.
> The function is written thus:
> CREATE FUNCTION dbo.fnc_CapArrayValue
> (@.MEASUREMENTID INT,@.TRACKINGID BIGINT,@.JET INT)
> RETURNS REAL AS
> BEGIN
> Declare @.Result REAL
> SET @.RESULT = (select @.JET from dbo.vw_CapArrayData
> where (measurement_id = @.measurementid) and (tracking_id = @.trackingid))
> RETURN @.Result
> END
> GO
This function appears funny to me. It will return the value in @.JET if
there is a matching row, else it will return NULL. This could be expressed
more clearly.
Avoid scalar UDFs that performs data access. This can cause quite severe
performance degradation, in queries that calls the UDF, as the query
more or less gets converted to a cursor behind the scenes.
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se
Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pr...oads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodin...ions/books.mspx|||>> I am trying to write a view that includes a column derived from a functio
n call. <<
Take a freshman course in BASIC Software Engineering. Try to be sober
on the days that that coupling and cohesion are discussed. It will
keep you from public embarassment in the future. You might also want
to Google over to Larry O'Brien's current column this month for a
reminder.
You even even put prefixes like "fnc_" on names! You never read
ISO-11179. Measurement_id? There is no name possible in a data model.
So very wrong! BIGINTs because you have more data than there are atoms
in the Universe!!
Almost everything. Forget the crashes; your whole mindset is wrong.
Post specs and we can try to get you something that is correct.
--CELKO--|||Are you always this condescending? I am relatively new to the world of
databases, not a seasoned veteran; hence the reason I am asking a question.
I appreciate what you have inputted, but not the attitude used to deliver
it.
BTW, I am in no way embarrassed as I am working on curing my ignorance and
appreciate all the help I can get.
Thomas
"--CELKO--" <jcelko212@.earthlink.net> wrote in message
news:1150410406.196985.12150@.y41g2000cwy.googlegroups.com...
> Take a freshman course in BASIC Software Engineering. Try to be sober
> on the days that that coupling and cohesion are discussed. It will
> keep you from public embarassment in the future. You might also want
> to Google over to Larry O'Brien's current column this month for a
> reminder.
> You even even put prefixes like "fnc_" on names! You never read
> ISO-11179. Measurement_id? There is no name possible in a data model.
> So very wrong! BIGINTs because you have more data than there are atoms
> in the Universe!!
>
> Almost everything. Forget the crashes; your whole mindset is wrong.
> Post specs and we can try to get you something that is correct.
> --CELKO--
>|||Thank you for your response, Mike,
Allow me to better describe what I am attempting to do without divulging
confidential information.
I have two views that I am joining together with related data. On the one
side is yield data related to particular failures. On the other side is data
from a related process generated during the manufacturing processes prior to
generating the yield data; this data is related by three of their fields.
The two views link together predictably and the data returned is valid.
However, I must also get a related value from an array table to insert into
the view I am creating; hence the reason I was exploring the use of a
function.
I hope this is more understandable, if not I'm screwed; this problem has me
at my wits end right now.
Thomas Mick
"Mike John" <Mike.John@.knowledgepool.com> wrote in message
news:uyz7m8KkGHA.4716@.TK2MSFTNGP03.phx.gbl...
> Does the same query executed against the view return results in a
> resonable time?
> If not then posting the view definition and the definitions and indexes of
> the underlying tables would give a few clues.
> Is this an extract of somethimg much more complicated - if not I cannot
> see much reason for using the function - unless you need it in a
> constraint or similar.
> Re-reading your post - is the function being used in a view definition,
> and itself retriving data from a view (assuming vw_CapArrayData is a
> view?) BTW you may get a deluge saying prefixing vw on the front of view
> names is a bad idea, which I happen to think it is - be warned.
> I suspect that the combination of a view based on a function, based on a
> view has caused the optimiser to get a tad and produce a poor
> execution plan.
> Mike John
> "Thomas Mick" <nospam@.nospam.com> wrote in message
> news:y2ikg.3677$Oh1.923@.news01.roc.ny...
>|||Erland,
Thank you for your constructive response. I truly appreciate it and will
learn accordingly.
Thomas Mick
"Erland Sommarskog" <esquel@.sommarskog.se> wrote in message
news:Xns97E429816C9FYazorman@.127.0.0.1...
> Thomas Mick (nospam@.nospam.com) writes:
> This function appears funny to me. It will return the value in @.JET if
> there is a matching row, else it will return NULL. This could be expressed
> more clearly.
> Avoid scalar UDFs that performs data access. This can cause quite severe
> performance degradation, in queries that calls the UDF, as the query
> more or less gets converted to a cursor behind the scenes.
>
> --
> Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se
> Books Online for SQL Server 2005 at
> http://www.microsoft.com/technet/pr...oads/books.mspx
> Books Online for SQL Server 2000 at
> http://www.microsoft.com/sql/prodin...ions/books.mspx|||Just ignore him Thomas, most be do - he's an ignorant, condesending idiot
who has a high opinion of himself, oh and watch out for his stuck in the
80's model thinking.
Don't let this single fool put you off posting here again!
Tony.
Tony Rogerson
SQL Server MVP
http://sqlblogcasts.com/blogs/tonyrogerson - technical commentary from a SQL
Server Consultant
http://sqlserverfaq.com - free video tutorials
"Thomas Mick" <nospam@.nospam.com> wrote in message
news:Hdnkg.3705$Oh1.2508@.news01.roc.ny...
> Are you always this condescending? I am relatively new to the world of
> databases, not a seasoned veteran; hence the reason I am asking a
> question. I appreciate what you have inputted, but not the attitude used
> to deliver it.
> BTW, I am in no way embarrassed as I am working on curing my ignorance and
> appreciate all the help I can get.
> Thomas
> "--CELKO--" <jcelko212@.earthlink.net> wrote in message
> news:1150410406.196985.12150@.y41g2000cwy.googlegroups.com...
>|||I have a feeling I already know the answer to this, but I have to ask
anyway; can a stored procedure be run from within a function? Or
alternatively, can I run a stored procedure from within a view?
You see, I need to insert this value into a column of a view I am creating
for an engineer; a stored procedure would most likely be the best method of
retrieving what I need.
Thomas Mick
"Anith Sen" <anith@.bizdatasolutions.com> wrote in message
news:eWGUFjMkGHA.1600@.TK2MSFTNGP04.phx.gbl...
> You cannot use Dynamic SQL inside functions. The workaround is to use a
> CASE expression like:
> SET @.r = ( SELECT CASE @.p WHEN 'value_1' THEN col_1
> WHEN 'value_2' THEN col_2
> ...
> WHEN 'value_n' THEN col_n
> END
> FROM dbo.vw_CapArrayData
> WHERE measurement_id = @.m_id
> AND tracking_id = @.t_id ) ;
> Alternatively you can create a procedure to get this information, however
> you'll have to make careful considerations for security and performance.
> --
> Anith
>