Update table based on nested select from the same table

I have a table of categories filled with some of our own data and data from an XML feed.  I have no access to the original data from the XML feed.

Data looks something like this at the moment

CategoryID    |     CatName      |    ParentID   |   XMLCode   |   XMLParent
  1                      Cars                     0                  1234              0
  2                      Bikes                    0                  9999              0
  3                      Mirrors                 0                  19673            1234
  4                      Handlebars            0                 96734            9999
  5                      Cheese                 0               <NULL>         <NULL>
  6                      French                  5               <NULL>         <NULL>

Each category can have a parent of another category so the eventual structure is a tree like listing.  The categories from the XML feed will get updated semi-regularly in case any get added or changed etc...  I need to be able to map the parentIDs for the XML categories based on the XMLCode and XMLParent.

Using the example above The ParentID For "Mirrors" would get set to "1" and the ParentID for "handlebars" would get set to "2".  These are arrived at using the XMLParent which are already present from the XML feed.  The "Cheese" and "French" records would be ignored as the XMLdata is not present.

Using this forum and other resources I have come up with the following which runs but does nothing to the data.  The table is called tbl_FPCat.

UPDATE    tblup
SET              tblup.ParentID = nested.CategoryID
FROM         tbl_FPCat AS tblup JOIN
                          (SELECT     CategoryID, XMLCode, XMLParent
                            FROM          tbl_FPCat
                            WHERE      XMLCode= XMLParent) AS nested ON tblup.XMLParent = nested.XMLCode
WHERE     (tblup.XMLCode <> NULL) OR (tblup.XMLCode <> '')

I dont even know if this is possible or even if I am on the right track at this point.  Any help greatly appreciated.  Anything not clear - just ask.

Who is Participating?
imran_fastConnect With a Mentor Commented:
try this

update a set a.ParentID = b.categoryid
from tbl_FPCat a
inner join tbl_fpcat b on
b.XMLCode = a.XMLParent
try this

update tbl_FPCat set ParentID = b.categoryid
from tbl_FPCat b
where b.XMLCode = tbl_FPCat.XMLParent
UPDATE    tblup
SET              tblup.ParentID = (select CategoryID from tblup T where T.XMLParent  = tblup.xmlcode)
WHERE     (tblup.XMLCode <> NULL) OR (tblup.XMLCode <> '')
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snavebelacAuthor Commented:
thanks for the response

when I run that I get the following error

"The column prefix 'tbl_FPCat' does not match with a table name or alias name used in the query."

which is odd...  I checked the names of everything and it is all correct  any thoughts?

snavebelacAuthor Commented:
that last respnse was to imran_fast
snavebelacAuthor Commented:

I tried that configuration once before - I tried again and I get this error...

"Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
The statement has been terminated."

the XMLCode column is unique apart from the NULLs and zero length strings which are being filtered.

Any ideas ?


snavebelacAuthor Commented:

That worked great - thanks - knew it had to be simple

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