Recommended way to search hierarchical data MSSQL2008 - sql-server-2008

Question

I have a table with the following contents:
CategoryID
ParentID
Name
I would like to have a search functionality that would search the whole hierarchy, for exmple this is the breadcrumb of a category:
Motorcycles/Japan/Kawasaki/600cc to 800cc/1998-2004
If someone searches for "600cc Kawasaki" I would like the above category to be returned. So the categorypath which has the most matches should return.
At the moment I came up with this:
IF ISNULL(#searchTerm, '') = ''
SET #searchTerm = '""'
DECLARE #Result TABLE (CategoryId int)
DECLARE CategoryCursor CURSOR LOCAL FAST_FORWARD FOR
SELECT CategoryId, ParentId, Name
FROM Category
WHERE FREETEXT([Name], #searchTerm)
OPEN CategoryCursor
DECLARE #CategoryId int
DECLARE #ParentId int
DECLARE #Name nvarchar(100)
FETCH NEXT FROM CategoryCursor INTO #CategoryId, #ParentId, #Name
WHILE ##FETCH_STATUS = 0
BEGIN
DECLARE #FullPath nvarchar(1000)
SET #FullPath = #Name
WHILE #ParentId <> 0
BEGIN
SELECT #ParentId = ParentId, #Name = [Name]
FROM Category
WHERE CategoryId = #ParentId
SET #FullPath = #Name + '\' + #FullPath
END
-- Check if #FullPath contains all of the searchterms
DECLARE #found bit
DECLARE #searchWords NVARCHAR(100)
DECLARE #searchText NVARCHAR(255)
DECLARE #pos int
SET #found = 1
SET #searchWords = #searchTerm + ' '
SET #pos = CHARINDEX(' ', #searchWords)
WHILE #pos <> 0
BEGIN
SET #searchText = LEFT(#searchWords, #pos - 1)
SET #searchWords = STUFF(#searchWords, 1, #pos, '')
SET #pos = CHARINDEX(' ', #searchWords)
IF #searchText = '' CONTINUE
IF #FullPath NOT LIKE '%' + #searchText + '%'
BEGIN
SET #found = 0
BREAK
END
END
IF #found = 1
INSERT INTO #Result VALUES(#CategoryId)
FETCH NEXT FROM CategoryCursor INTO #CategoryId, #ParentId, #Name
END
CLOSE CategoryCursor
DEALLOCATE CategoryCursor
SELECT *
FROM Category
WHERE categoryID IN (SELECT categoryId FROM #Result)
This will first find all catagorynames which contain any of the searchwords. Problem is, I don't want "600cc" for other brands to return, only the one which is related to "Kawasaki".
So next I build the breadcrumb for the current category and see if it contains all of the searchwords.
It works but I think it is ineffective so i'm looking for a better method.
Perhaps storing the complete path as text in a new column and search on that?

Answer 1

I'd suggest using the hierarchyid which is in 2008. You would essentially set your hierarchy like this
/1/ - Root Node
/1/1/ - Motorcycles
/1/1/1/ - Japan
/1/1/1/1/ - Kawasaki
/1/1/1/2/ - Honda
/1/1/2/ - US
/1/1/2/1/ - Harley.
Then you can use the hierarchyid to get the entire tree from your 600cc 1984 kawasaki all the way up to motorcycles.
Here's a code sample from Programming Microsoft SQL Server 2008
CREATE FUNCTION dbo.fnGetFullDisplayPath(#EntityNodeId hierarchyid) RETURNS varchar(max) AS
BEGIN
DECLARE #EntityLevelDepth smallint
DECLARE #LevelCounter smallint
DECLARE #DisplayPath varchar(max)
DECLARE #ParentEmployeeName varchar(max)
-- Start with the specified node
SELECT #EntityLevelDepth = NodeId.GetLevel(),
#DisplayPath = EmployeeName
FROM Employee
WHERE NodeId = #EntityNodeId
-- Loop through all its ancestors
SET #LevelCounter = 0
WHILE #LevelCounter < #EntityLevelDepth
BEGIN
SET #LevelCounter = #LevelCounter + 1
SELECT #ParentEmployeeName = EmployeeName
FROM Employee WHERE NodeId = (SELECT NodeId.GetAncestor(#LevelCounter)
FROM Employee
WHERE NodeId = #EntityNodeId)
-- Prepend the ancestor name to the display path
SET #DisplayPath = #ParentEmployeeName + ' > ' + #DisplayPath
END
RETURN(#DisplayPath)
END
My /1/1/2 representation is the string representation. In the database you'd actually see the hex representation (e.g. 0x79).
There are a few key functions on the hierarchyid.
declare #motorcycleAncestor hieararchyid
select #motorcycleAncestor = nodeId.GetAncestor(1)
from parts
where Label = 'motorcycle'
select * from Parts
where Node.GetAncestor(1) = #motorcyleAncestor;
This query does a couple things. First, it gets the hierarchy id for the node that contains "Motorcycle" as the label. (I assume the hiearchy field is named 'nodeid' but you can obviously call it whatever.)
Next, it takes this node value and finds all the immediate children of motorcycles (who's ancestor, 1 level up, is the motorcycle node. You can actually specify any value, like GetAncestor(3) would be the ancestor 3 levels up). So in that case, it would find Japan, US, Germany etc.
There is another method, called IsDescendantOf(node). You can use it like this:
declare #motorcycleAncestor hieararchyid
select #motorcycleAncestor = nodeId.GetAncestor(1)
from parts
where Label = 'motorcycle'
select * from Parts
where Node.IsDescendantOf(#motorcycleAncestor) = 1
This would return all items that are children (of any level) underneath motorcycles. It would actually also include Motorcycles.
You can combine these in different ways. For example, we're using them in an org chart of sorts. We have the ability to show results for a single user, or for a user and his siblings (everyone at the exact same level) and a user and all his descendants.
So I could show your information, or I could show everyone in your department, or I could show everyone in your company.