?
Solved

TSQL XML question

Posted on 2014-03-02
6
Medium Priority
?
310 Views
Last Modified: 2014-03-18
I have an document where i need to look to see if an element exists and has data.  

So i use @xml.exist and @xml.value to first check it exists and then if it has a value.

I need to do this with 50 or so elements so i would like to write a function that does both tests.  This will make my code a bit easier to read.

So i have tried but there is something wrong with it as it always says there is a value.  Maybe it is not possible to do this.  Here is my function.  Can anyone see what is wrong with it?

alter FUNCTION pharos_Exists
(
	-- Add the parameters for the function here
	@xml xml,
	@variable nvarchar(100) 
)
RETURNS int 
AS
BEGIN
	-- Declare the return variable here
  declare @exists int ;
  --'(SweAAABas2012/U1SuprarenalDiameter)[1]'
  
  set @exists = 1 ;

  if (@xml.exist( 'sql:variable("@variable")' ) = 0) or (@xml.value( 'sql:variable("@variable")', 'nvarchar(100)') = '')
    set @exists = 0 ;
	
	-- Return the result of the function
  return @exists 

END
GO

Open in new window

0
Comment
Question by:soozh
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
6 Comments
 
LVL 35

Expert Comment

by:Robert Schutt
ID: 39898807
You seem to be checking variable itself, not the corresponding value in the xml document.

If the commented out "SweAAABas2012/U1SuprarenalDiameter" is an example of what you want to search for, then I don't have a real easy solution, but keep reading ;-)

If you just need 1 node then you can use this:
alter FUNCTION pharos_Exists
(
	@xml xml,
	@variable nvarchar(100)
)
RETURNS int 
AS
BEGIN
  declare @exists int ;
  set @exists = 1 ;
  
  if (@xml.exist( '//*[local-name()=sql:variable("@variable")]' ) = 0)
  or (@xml.value( '(//*[local-name()=sql:variable("@variable")])[1]', 'nvarchar(100)') = '')
    set @exists = 0 ;
	
  return @exists 

END
GO

Open in new window

If you do need to check for a path like "SweAAABas2012/U1SuprarenalDiameter" then you could use this: (call it with the 2 node names separately)
alter FUNCTION pharos_Exists
(
	@xml xml,
	@variable nvarchar(100),
	@variable2 nvarchar(100)
)
RETURNS int 
AS
BEGIN
  declare @exists int ;
  set @exists = 1 ;
  
  if (@xml.exist( '//*[local-name()=sql:variable("@variable")]/*[local-name()=sql:variable("@variable2")]' ) = 0)
  or (@xml.value( '(//*[local-name()=sql:variable("@variable")]/*[local-name()=sql:variable("@variable2")])[1]', 'nvarchar(100)') = '')
    set @exists = 0 ;
	
  return @exists 

END
GO

Open in new window

0
 

Author Comment

by:soozh
ID: 39898959
Thanks.

You are correct that i am looking for something like "SweAAABas2012/U1SuprarenalDiameter".  

I am Always looking for something in the format "SweAAABas2012/ xxxx "

So maybe i can hard code that in my function instead of @variable?

Can you provide the syntax?  i really dont understand xquery!
0
 
LVL 35

Accepted Solution

by:
Robert Schutt earned 2000 total points
ID: 39898984
Yeah sure:
alter FUNCTION pharos_Exists
(
	@xml xml,
	@variable nvarchar(100)
)
RETURNS int 
AS
BEGIN
  declare @exists int ;
  set @exists = 1 ;
  
  if (@xml.exist( '//SweAAABas2012/*[local-name()=sql:variable("@variable")]' ) = 0)
  or (@xml.value( '(//SweAAABas2012/*[local-name()=sql:variable("@variable")])[1]', 'nvarchar(100)') = '')
    set @exists = 0 ;
	
  return @exists 

END
GO

Open in new window

If you have an exact location in the document then you can use that for example /root/data/record/SweAAABas2012 instead of //SweAAABas2012 which searches for that node on any level in the document.
0
Will your db performance match your db growth?

In Percona’s white paper “Performance at Scale: Keeping Your Database on Its Toes,” we take a high-level approach to what you need to think about when planning for database scalability.

 
LVL 35

Expert Comment

by:Robert Schutt
ID: 39899026
By the way, if you're gonna call this function 50 times then there may be a more efficient way of doing this (using .nodes if I remember correctly), but I'd have to look into that and know more about what you need to do exactly.
0
 

Author Comment

by:soozh
ID: 39899054
i would be interested in the nodes solution.

What i am doing is validating some xml and i need to check whether a node exits and if it does if it has a value..
0
 
LVL 35

Expert Comment

by:Robert Schutt
ID: 39899081
There's some Examples here: http://technet.microsoft.com/en-us/library/ms188282.aspx

A start could be:
DECLARE @x xml 
SET @x='<root><some><more><SweAAABas2012><U1SuprarenalDiameter>10mm</U1SuprarenalDiameter><U1SuprarenalDiameter2></U1SuprarenalDiameter2></SweAAABas2012></more></some></root>'

SELECT CASE WHEN ISNULL(T.c.value('U1SuprarenalDiameter[1]', 'nvarchar(100)'), '') = '' THEN 0 ELSE 1 END AS U1SuprarenalDiameter -- 1 because there is data
	, CASE WHEN ISNULL(T.c.value('U1SuprarenalDiameter2[1]', 'nvarchar(100)'), '') = '' THEN 0 ELSE 1 END AS U1SuprarenalDiameter2 -- 0 because it's empty
	, CASE WHEN ISNULL(T.c.value('U1SuprarenalDiameter3[1]', 'nvarchar(100)'), '') = '' THEN 0 ELSE 1 END AS U1SuprarenalDiameter3 -- 0 because it's missing
FROM   @x.nodes('//SweAAABas2012') T(c)

Open in new window

But if you can tell me how you need the data presented, then maybe this can be shortened, although that might actually hurt performance...
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

How to leverage one TLS certificate to encrypt Microsoft SQL traffic and Remote Desktop Services, versus creating multiple tickets for the same server.
In this article we will get to know that how can we recover deleted data if it happens accidently. We really can recover deleted rows if we know the time when data is deleted by using the transaction log.
In this brief tutorial Pawel from AdRem Software explains how you can quickly find out which services are running on your network, or what are the IP addresses of servers responsible for each service. Software used is freeware NetCrunch Tools (https…
In this video you will find out how to export Office 365 mailboxes using the built in eDiscovery tool. Bear in mind that although this method might be useful in some cases, using PST files as Office 365 backup is troublesome in a long run (more on t…

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question