Loop for extracting attributes of elements XML - sql-server

Question

I need to extract all attributes from a long list of various elements. Therefore, I'm seeking to build a loop going through all of my elements and return their attributes.
Through several posts I have been able to write the code below. However, I have more than a 1000 elements why I would extremely glad if it somehow is possible to build a loop around the latter part rather than copying it for all elements.
with cte as
(
select cast(
'<schema fwRel="2">
<taxFormId isPrimeKey="true" fkRef="C1-TXFRM" mapField="TAX_FORM_ID" dataType="string"/>
<formType fkRef="C1-FRMTY" mapField="FORM_TYPE_CD" dataType="string"/>
<bo suppress="true" required="true" fkRef="F1-BUSOB" mapField="BUS_OBJ_CD" dataType="string"/>
<transferReason mdField="C1_TXF_TFRRSN_FLG" dataType="lookup" mapXML="BO_DATA_AREA" lookup="C1_TXF_TFRRSN_FLG"/>
</schema>' as xml) xml_col
)
select cte.xml_col.value('(/schema/taxFormId/#fkRef)[1]', 'varchar(100)') as Dummy1
cte.xml_col.value('(/schema/taxFormId/#mapField)[1]', 'varchar(100)') as Dummy2
cte.xml_col.value('(/schema/taxFormId/#dataType)[1]', 'varchar(100)') as Dummy3
cte.xml_col.value('(/schema/taxFormId/#mapXML)[1]', 'varchar(100)') as Dummy4
from cte
I hope I have provided enough information

Answer 1

An easy way to get attributes listed:
with cte as
(
select cast(
'<schema fwRel="2">
<taxFormId isPrimeKey="true" fkRef="C1-TXFRM" mapField="TAX_FORM_ID" dataType="string" />
<formType fkRef="C1-FRMTY" mapField="FORM_TYPE_CD" dataType="string" />
<bo suppress="true" required="true" fkRef="F1-BUSOB" mapField="BUS_OBJ_CD" dataType="string" />
<transferReason mdField="C1_TXF_TFRRSN_FLG" dataType="lookup" mapXML="BO_DATA_AREA" lookup="C1_TXF_TFRRSN_FLG" />
</schema>' as xml) xml_col
)
--The query uses .nodes(N'/schema/*') to list all nodes below <schema> and .nodes(N'#*') to list all attributes within this node:
select nd.value(N'local-name(.)',N'nvarchar(max)') AS NodeName
,attr.value(N'local-name(.)',N'nvarchar(max)') AS AttrName
,attr.value(N'.',N'nvarchar(max)') AS AttrValue
from cte
OUTER APPLY xml_col.nodes(N'/schema/*') AS A(nd)
OUTER APPLY A.nd.nodes(N'#*') AS B(attr)
The result:
taxFormId isPrimeKey true
taxFormId fkRef C1-TXFRM
taxFormId mapField TAX_FORM_ID
taxFormId dataType string
formType fkRef C1-FRMTY
formType mapField FORM_TYPE_CD
formType dataType string
bo suppress true
bo required true
bo fkRef F1-BUSOB
bo mapField BUS_OBJ_CD
bo dataType string
transferReason mdField C1_TXF_TFRRSN_FLG
transferReason dataType lookup
transferReason mapXML BO_DATA_AREA
transferReason lookup C1_TXF_TFRRSN_FLG
If you need a statement like the one in your example one could create it dynamically (as string) and use EXEC to execute this (dynamic SQL).

Answer 2

It may be a little over-kill, but I often use a TVF to parse and hash large XML files. The function will return the data in a parent/child hierarchy structure with range keys R1/R2.
For example:
Declare #XML xml='
<schema fwRel="2">
<taxFormId isPrimeKey="true" fkRef="C1-TXFRM" mapField="TAX_FORM_ID" dataType="string"/>
<formType fkRef="C1-FRMTY" mapField="FORM_TYPE_CD" dataType="string"/>
<bo suppress="true" required="true" fkRef="F1-BUSOB" mapField="BUS_OBJ_CD" dataType="string"/>
<transferReason mdField="C1_TXF_TFRRSN_FLG" dataType="lookup" mapXML="BO_DATA_AREA" lookup="C1_TXF_TFRRSN_FLG"/>
</schema>'
Select * from [dbo].[udf-XML-Hier](#XML) Order by R1
Returns
You'll notice there are columns for Element Name, Attribute Name, XPath, Title (optional), and Value. The R1,R2,Lvl,ID and PT are all derived.
Being a TVF, you could apply any WHERE or ORDER desired
The UDF (with original source) if interested
CREATE FUNCTION [dbo].[udf-XML-Hier](#XML xml)
Returns Table
As Return
with cte0 as (
Select Lvl = 1
,ID = Cast(1 as int)
,Pt = Cast(NULL as int)
,Element = x.value('local-name(.)','varchar(150)')
,Attribute = cast('' as varchar(150))
,Value = x.value('text()[1]','varchar(max)')
,XPath = cast(concat(x.value('local-name(.)','varchar(max)'),'[' ,cast(Row_Number() Over(Order By (Select 1)) as int),']') as varchar(max))
,Seq = cast(10000001 as varchar(max))
,AttData = x.query('.')
,XMLData = x.query('*')
From #XML.nodes('/*') a(x)
Union All
Select Lvl = p.Lvl + 1
,ID = Cast( (Lvl + 1) * 1024 + (Row_Number() Over(Order By (Select 1)) * 2) as int ) * 10
,Pt = p.ID
,Element = c.value('local-name(.)','varchar(150)')
,Attribute = cast('' as varchar(150))
,Value = cast( c.value('text()[1]','varchar(max)') as varchar(max) )
,XPath = cast(concat(p.XPath,'/',c.value('local-name(.)','varchar(max)'),'[',cast(Row_Number() Over(PARTITION BY c.value('local-name(.)','varchar(max)') Order By (Select 1)) as int),']') as varchar(max) )
,Seq = cast(concat(p.Seq,' ',10000000+Cast( (Lvl + 1) * 1024 + (Row_Number() Over(Order By (Select 1)) * 2) as int ) * 10) as varchar(max))
,AttData = c.query('.')
,XMLData = c.query('*')
From cte0 p
Cross Apply p.XMLData.nodes('*') b(c)
)
, cte1 as (
Select R1 = Row_Number() over (Order By Seq),A.*
From (
Select Lvl,ID,Pt,Element,Attribute,Value,XPath,Seq From cte0
Union All
Select Lvl = p.Lvl+1
,ID = p.ID + Row_Number() over (Order By (Select NULL))
,Pt = p.ID
,Element = p.Element
,Attribute = x.value('local-name(.)','varchar(150)')
,Value = x.value('.','varchar(max)')
,XPath = p.XPath + '/#' + x.value('local-name(.)','varchar(max)')
,Seq = cast(concat(p.Seq,' ',10000000+p.ID + Row_Number() over (Order By (Select NULL)) ) as varchar(max))
From cte0 p
Cross Apply AttData.nodes('/*/#*') a(x)
) A
)
Select A.R1
,R2 = IsNull((Select max(R1) From cte1 Where Seq Like A.Seq+'%'),A.R1)
,A.Lvl
,A.ID
,A.Pt
,A.Element
,A.Attribute
,A.XPath
,Title = Replicate('|---',Lvl-1)+Element+IIF(Attribute='','','#'+Attribute)
,A.Value
From cte1 A
/*
Source: http://beyondrelational.com/modules/2/blogs/28/posts/10495/xquery-lab-58-select-from-xml.aspx
Declare #XML xml='<person><firstname preferred="Annie" nickname="BeBe">Annabelle</firstname><lastname>Smith</lastname></person>'
Select * from [dbo].[udf-XML-Hier](#XML) Order by R1
*/