SQL Server XQuery修改

Question

I am writing a T-SQL UDF and trying to modify an xml variable with values fetched by a cursor. The code executes fine, but the modifications of the xml variable doesn't take place.

The code goes as follows:

CREATE FUNCTION GetDateBlockXmlFromTable(@occupieddates occupieddates READONLY)
RETURNS XML
AS
BEGIN
   DECLARE @xmlresult xml;
   DECLARE @datefrom datetime, @dateto datetime;

   SELECT @xmlresult = '<root><DateBlocks/></root>';

   DECLARE GetDateBlockXmlFromTable_Cur 
   CURSOR FOR 
        SELECT DateFrom, DateTo FROM @occupieddates

   OPEN GetDateBlockXmlFromTable_Cur 

   FETCH NEXT FROM GetDateBlockXmlFromTable_Cur INTO @datefrom, @dateto

   WHILE @@FETCH_STATUS = 0
   BEGIN
      SET @xmlresult.modify('insert <DateBlock><FirstDay>"{sql:variable("@datefrom")}"</FirstDay><EndDay>"{sql:variable("@dateto")}"</EndDay></DateBlock> as last into (/DateBlocks)[1]');

      FETCH NEXT FROM GetDateBlockXmlFromTable_Cur INTO @datefrom, @dateto
   END

   CLOSE GetDateBlockXmlFromTable_Cur
   DEALLOCATE GetDateBlockXmlFromTable_Cur

   RETURN @xmlresult;
END

The occupieddates readonly input table goes like this:

CREATE TYPE occupieddates  AS TABLE 
(
   DateFrom datetime, 
   DateTo datetime, 
)

Answer 1

Simply change

as last into (/DateBlocks)[1]

to

as last into (/root/DateBlocks)[1]

Either you may consider changing result variable declaration as SELECT @xmlresult = '<DateBlocks/>' .

And also you may cosider using for xml statement:

CREATE FUNCTION GetDateBlockXmlFromTable(@occupieddates occupieddates READONLY)
RETURNS XML
AS
BEGIN
    DECLARE @xmlresult xml;

    set @xmlresult = (
        select
            (select
                '"' + convert(varchar, DateFrom, 126) + '"'  as FirstDay,
                '"' + convert(varchar, DateTo, 126) + '"' as EndDay
            from
                @occupieddates
            for xml path('DateBlock'), type)
        for xml path('DateBlocks')--, root('root') -- depending on need
    )

    return @xmlresult;
END

Answer 2

Seems like you should change

...into (/DateBlocks)...

to

...into (/root/DateBlocks)...