Types don't match between the anchor and the recursive part in column of recursive query

sql, sql-server, t-sql

Solution

Try changing the query to cast the varchars to VARCHAR(MAX).

Something like

DECLARE @CategoryId AS int = 217;
WITH Categories AS
(
   SELECT ParentCategoryId, CategoryName, CAST('' AS VARCHAR(MAX)) AS strCategory
   FROM Category 
   WHERE CategoryId = @CategoryId

   UNION ALL

   SELECT c.ParentCategoryId, c.CategoryName,
       CAST((c.CategoryName + ': ' + cts.strCategory) AS VARCHAR(MAX)) AS strCategory  
   FROM Category AS c
   JOIN Categories AS cts
   ON c.CategoryId = cts.ParentCategoryId
)

SELECT TOP 1 CategoryName, LEN(CategoryName) AS strLength
FROM Categories
ORDER BY strLength DESC

Problem

Given a category @categoryId, the query should recursively navigate to the top most super-category, which has been accomplished. Now I'd like also to generate all along a string which would be the concatenation of all the CategoryName in the process. ``` DECLARE @CategoryId AS int = 217; WITH Categories AS ( SELECT ParentCategoryId, CategoryName, '' AS strCategory FROM Category WHERE CategoryId = @CategoryId UNION ALL SELECT c.ParentCategoryId, c.CategoryName, (c.CategoryName + ': ' + cts.strCategory) AS strCategory FROM Category AS c JOIN Categories AS cts ON c.CategoryId = cts.ParentCategoryId ) SELECT TOP 1 CategoryName, LEN(CategoryName) AS strLength FROM Categories ORDER BY strLength DESC ``` With the above code I'm getting the following error: ``` Types don't match between the anchor and the recursive part in column "strCategory" of recursive query "Categories". ``` Thanks for helping

Original source