Creating a string - Cursor or Case

Hi all,
I need to perform a validation test on fields in stored data for each row an
d
updating the Comment field with the reasons why test failed where appropriat
e.
The real scenario has quite a number of fields for me to use a CASE also I
want to avoid using a looping mechanism to build the string to update commen
t
field. I'm a novice of sort so I'm curious as to wether there is another
approach I use?
CREATE TABLE [dbo].[TableA] (
[StartDate] [datetime] NULL ,
[EndDate] [datetime] NULL ,
[Quantity] [int] NULL ,
[Bar_Code] [varchar] (10) NULL ,
[Comment] [varchar] (255)NULL
) ON [PRIMARY]
GO
My initial approch is roughly something like this
UPDATE [dbo].[TableA]
SET Comment =
CASE WHEN (0 = isnumeric(quantity) AND startdate > (getdate()) AND enddate <
(getdate()) THEN 'Invalid quantity, startdate in future, enddate in past'
WHEN (0 = isnumeric(quantity) AND startdate < (getdate()) AND enddate >
(getdate()) THEN 'Invalid quantity' END
WHERE (0 = isnumeric(quantity)
or startdate > (getdate())
or enddate < (getdate())
or 0 = isdate (startdate)
or 0 = isdate (enddate))
obelix
"Whether you think you can or you think you cant you are right" ... Anon
Message posted via droptable.com
http://www.droptable.com/Uwe/Forum...server/200703/1Put each test in an individual CASE, concatenating the results to get
one string. The SUBSTRING is to get rid of the leading comma and
space that the first message will have.
UPDATE [dbo].[TableA]
SET Comment = SUBSTRING(
CASE WHEN 0 = isnumeric(quantity)
THEN ', Invalid quantity'
ELSE ''
END +
CASE WHEN startdate > getdate()
THEN ', startdate in future'
ELSE ''
END +
CASE WHEN enddate < getdate()
THEN ', enddate in past'
ELSE ''
END +
CASE WHEN 0 = isdate (startdate)
THEN ', invalid startdate'
ELSE ''
END +
CASE WHEN 0 = isdate (enddate)
THEN ', enddate in past'
ELSE ''
END, 3, 100)
WHERE (0 = isnumeric(quantity)
or startdate > getdate()
or enddate < getdate()
or 0 = isdate (startdate)
or 0 = isdate (enddate))
Roy Harvey
Beacon Falls, CT
On Sun, 18 Mar 2007 11:08:00 GMT, "obelix via droptable.com"
<u24035@.uwe> wrote:

>Hi all,
>I need to perform a validation test on fields in stored data for each row a
nd
>updating the Comment field with the reasons why test failed where appropria
te.
>The real scenario has quite a number of fields for me to use a CASE also I
>want to avoid using a looping mechanism to build the string to update comme
nt
>field. I'm a novice of sort so I'm curious as to wether there is another
>approach I use?
>CREATE TABLE [dbo].[TableA] (
> [StartDate] [datetime] NULL ,
> [EndDate] [datetime] NULL ,
> [Quantity] [int] NULL ,
> [Bar_Code] [varchar] (10) NULL ,
> [Comment] [varchar] (255)NULL
> ) ON [PRIMARY]
>GO
>My initial approch is roughly something like this
>UPDATE [dbo].[TableA]
>SET Comment =
>CASE WHEN (0 = isnumeric(quantity) AND startdate > (getdate()) AND enddate
<
>(getdate()) THEN 'Invalid quantity, startdate in future, enddate in past'
>WHEN (0 = isnumeric(quantity) AND startdate < (getdate()) AND enddate >
>(getdate()) THEN 'Invalid quantity' END
>WHERE (0 = isnumeric(quantity)
>or startdate > (getdate())
>or enddate < (getdate())
>or 0 = isdate (startdate)
>or 0 = isdate (enddate))|||Roy's method looks best for actually DOING the update. I will point out a
significant performance problem though. Your initial INSERT into the table
probably puts an empty string or NULL into the Comment field. Thus EVERY
row that gets updated will have to be forwarded (if a HEAP table) or have
the page possibly reordered/split (if table has clustered index) since the
Comment for those rows with a problem will be non-zero in length. This will
quickly result in VERY fragmented data and poor performance.
You may also wish to put in a tinyint field to track whether or not the data
has been scanned or not and set it to a specific value once you have done an
evaluation on a row. If indexed, this column could speed performance by
avoiding table scans for each update sweep once you get a large number of
rows in the table.
TheSQLGuru
President
Indicium Resources, Inc.
"obelix via droptable.com" <u24035@.uwe> wrote in message
news:6f5c7e6489060@.uwe...
> Hi all,
> I need to perform a validation test on fields in stored data for each row
> and
> updating the Comment field with the reasons why test failed where
> appropriate.
> The real scenario has quite a number of fields for me to use a CASE also I
> want to avoid using a looping mechanism to build the string to update
> comment
> field. I'm a novice of sort so I'm curious as to wether there is another
> approach I use?
> CREATE TABLE [dbo].[TableA] (
> [StartDate] [datetime] NULL ,
> [EndDate] [datetime] NULL ,
> [Quantity] [int] NULL ,
> [Bar_Code] [varchar] (10) NULL ,
> [Comment] [varchar] (255)NULL
> ) ON [PRIMARY]
> GO
> My initial approch is roughly something like this
> UPDATE [dbo].[TableA]
> SET Comment =
> CASE WHEN (0 = isnumeric(quantity) AND startdate > (getdate()) AND enddate
> <
> (getdate()) THEN 'Invalid quantity, startdate in future, enddate in past'
> WHEN (0 = isnumeric(quantity) AND startdate < (getdate()) AND enddate >
> (getdate()) THEN 'Invalid quantity' END
> WHERE (0 = isnumeric(quantity)
> or startdate > (getdate())
> or enddate < (getdate())
> or 0 = isdate (startdate)
> or 0 = isdate (enddate))
> --
> obelix
> "Whether you think you can or you think you cant you are right" ... Anon
> Message posted via droptable.com
> http://www.droptable.com/Uwe/Forum...server/200703/1
>