CTE - Recursive SQL

> Thank you both for pointing me in the right direction. I've updated my question a little bit. Now i understand how to write the CTE query, but i'm running into issues with maxrecursion of 32767. Does any of you have an idea how to bypass that?

If you hit that limit, there is either an error in your query, or you have cycles in the data. I tried the table, the INSERT statements and the query in your first post, and it completed successfully. I did not try the .Net code you had.

That said, usually when you traverse a tree, you have an initial condition, for instance to start at the top level:

WITH CategoryRecursive AS
    (SELECT CategoryId, ParentCategoryIdFROM Category--->          WHERE  ParentCategoryID IS NULLUNIONALLSELECT CR.CategoryId, C.ParentCategoryIdFROM Category AS C INNERJOIN CategoryRecursive AS CRON C.CategoryId = CR.ParentCategoryId
    )SELECT * FROM CategoryRecursive AS CR2ORDERBY CR2.ParentCategoryId, CR2.CategoryId

Note: in your sample you had ParentCategoryId = 0 for the root, but it's more common to use NULL.

Then again, you mentioned about aggregation on all levels, and that may call for a different model to query the tree, but I don't think you have come that far yet.

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Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
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