Insert/update based on dynamic XML - sql-server

Question

I have following XML:
<NewDataSet>
<Data>
<Id>560f05b2-b215-4fea-9ac6-7f012fbca331</Id>
<Number>384D25334E04593B6DE9955E72F413F8A0A828FF</Number>
<CurrentDate>2012-11-21T09:09:26+00:00</CurrentDate>
</Data>
<Data>
<Id>9cff574b-59ea-4cbd-a2db-9ed02b6cc602</Id>
<Number>384D25334E04593B6DE9955E72F413F8A0A828FF</Number>
<Location>Town</Location>
<CurrentDate>2012-11-21T09:09:53+00:00</CurrentDate>
</Data>
</NewDataSet>
I'm trying to write a query that will inster new record or update existing one based on given xml. The problem is I cannot use predefined names of columns, becuase table straucture sometimes is changing. So the idea is to generate dynamic query and apply it. So far I've got following thing:
SET NOCOUNT OFF;
DECLARE #TableName nvarchar(50)
DECLARE #TableData xml
DECLARE #Query nvarchar(max)
DECLARE #Id uniqueidentifier
DECLARE #CurrentDate datetime
-- declare cursor
DECLARE cursor_inserting CURSOR LOCAL FAST_FORWARD FOR
SELECT
r.value('fn:local-name(.)', 'nvarchar(50)'),
r.query('.')
FROM #Data.nodes('//NewDataSet/*') AS records(r)
ORDER BY r.value('fn:local-name(.)', 'nvarchar(50)')
-- open cursor
OPEN cursor_inserting
FETCH NEXT FROM cursor_inserting INTO #TableName, #TableData
WHILE ##FETCH_STATUS = 0
BEGIN
-- Get id
SELECT #Id = o.value('Id[1]', 'uniqueidentifier') FROM #TableData.nodes('*') as n(o)
SELECT #CurrentDate = o.value('CurrentDate[1]', 'datetime') FROM #TableData.nodes('*') as n(o)
SET #Query = NULL
-- temporary update query
SET #UpdateTemp = NULL
SELECT #UpdateTemp = COALESCE(#UpdateTemp + ', ', '') + o.value('fn:local-name(.)', 'nvarchar(50)') + ' = ''' + CAST(o.query('text()') as nvarchar(4000)) + '''' FROM #TableData.nodes('/*/*') as n(o)
SET #UpdateTemp = 'UPDATE ' + #TableName + ' SET ' + #UpdateTemp + ' WHERE Id = ''' + CAST(#Id as nvarchar(40)) + ''''
-- temporary insert query
SET #Insert1Temp = NULL
SELECT #Insert1Temp = COALESCE(#Insert1Temp + ', ', '') + o.value('fn:local-name(.)', 'nvarchar(50)') FROM #TableData.nodes('/*/*') as n(o)
SET #Insert2Temp = NULL
SELECT #Insert2Temp = COALESCE(#Insert2Temp + ', ', '') + '''' + CAST(o.query('text()') as nvarchar(4000)) + '''' FROM #TableData.nodes('/*/*') as n(o)
SET #InsertTemp = 'INSERT INTO ' + #TableName + ' ( ' + #Insert1Temp + ' ) VALUES ( ' + #Insert2Temp + ' )'
IF #TableName = 'Data'
BEGIN
IF EXISTS (SELECT * FROM Data WHERE Id = #Id)
BEGIN
IF EXISTS (SELECT * FROM tblAudit WHERE Id = #Id AND CurrentDate < #CurrentDate)
BEGIN
SET #Query = #UpdateTemp
END
END
ELSE
BEGIN
SET #Query = #InsertTemp
END
END
IF #Query IS NOT NULL
BEGIN
SELECT #Query
EXEC (#Query)
END
END
FETCH NEXT FROM cursor_inserting INTO #TableName, #TableData
END
CLOSE cursor_inserting
DEALLOCATE cursor_inserting
If there is any better way to achive this inside SQL I would like to know, I know that I can do this outside SQL in my application code, but I would like to have it in one place in stored procedure to provide xml and have required action taken.
UPDATE 1
I would like to clarify that my main problem is query proper generation based on XML. The different way of handling instert/update is nice to see, but as addition
UPDATE 2
There can be more than 1 table in xml. E.g. not only Data but also Data2
UPDATE 3
I've update what I have now - and it is now generating proper Insert/Update however I now have issues with conversion. E.g. Date string is in xml format and sql doesn't want to convert it automaticaly. So my next step is get proper column type from database and instead of generate query instert directly from xml.I hope this will work.

Answer 1

Yes.
You can use MERGE and SQL XQuery to do it in one statement.
Something like...
merge Data as target
using
(
select
x.q.value('Id[1]','uniqueidentifier') as ID,
x.q.value('Number[1]','varchar(50)') as Number,
x.q.value('Location[1]','varchar(50)') as Town,
x.q.value('CurrentDate[1]','datetime') as CurrentDate
from
#TableData.nodes('/NewDataSet/Data')x(q)
) as Source (ID,Number,Town,CurrentDate)
on target.id=source.id
when matched and target.CurrentDate < source.CurrentDate then
update set
Number = source.number,
town = source.town,
currentdate = source.currentdate
when not matched then
insert (ID,number,town,currentdate)
values (source.id,source.number,source.town,source.currentdate);