Getting XML from SQL

--------------------------------------------------------------------
SELECT * FROM tempPK
Result:
c
---
211
311
--------------------------------------------------------------------
SELECT * FROM tempPK FOR XML AUTO, TYPE
Result:

--------------------------------------------------------------------
SELECT * FROM tempPK FOR XML AUTO, TYPE
Result:
211311
--------------------------------------------------------------------
SELECT * FROM tempPK FOR XML RAW('Cust'), ELEMENTS
Result:
134
--------------------------------------------------------------------
Add Null value.

SELECT * FROM tempPK
Result:
c
---
211
NULL
311

SELECT * FROM tempPK where c = null FOR XML AUTO, ELEMENTS

Result:
No xml will be generated.

SELECT * FROM tempPK FOR XML AUTO, ELEMENTS XSINIL