Question: I have a view which I want to derive from a recursive query.
The query is of the same structure as this one here: http://forums.asp.net/t/1207101.aspx
And represents a treeview as an ordered dataset.
How can I create a view which does this:
;WITH Tree (ID, [NAME], PARENT_ID, Depth, Sort) AS
(
SELECT ID, [NAME], PARENT_ID, 0 AS Depth, CONVERT(varchar(255), [Name]) AS Sort FROM Category
WHERE PARENT_ID = 0
UNION ALL
SELECT CT.ID, CT.[NAME], CT.PARENT_ID, Parent.Depth + 1 AS Depth,
CONVERT(varchar(255), Parent.Sort + ' | ' + CT.[NAME]) AS Sort
FROM Category CT
INNER JOIN Tree as Parent ON Parent.ID = CT.PARENT_ID
)
-- HERE IS YOUR TREE, Depths gives you the level starting with 0 and Sort is the Name based path
SELECT ID, [NAME], PARENT_ID, Depth, Sort FROM Tree
ORDER BY Sort
SQL Server CREATE VIEW First, specify the name of the view after the CREATE VIEW keywords. The schema_name is the name of the schema to which the view belongs. Second, specify a SELECT statement ( select_statement ) that defines the view after the AS keyword. The SELECT statement can refer to one or more tables.
Recursion is achieved by WITH statement, in SQL jargon called Common Table Expression (CTE). It allows to name the result and reference it within other queries sometime later.
Recursive CTE's Execution Order The first step is, execute the initial query (anchor member) which returns the base result set which is used for the next iteration. The second step is, execute the recursive query with the input result set from the previous iteration.
It should be as simple as:
CREATE VIEW YourViewName
AS
WITH Tree (ID, [NAME], PARENT_ID, Depth, Sort) AS
(
SELECT ID, [NAME], PARENT_ID, 0 AS Depth, CONVERT(varchar(255), [Name]) AS Sort
FROM Category
WHERE PARENT_ID = 0
UNION ALL
SELECT CT.ID, CT.[NAME], CT.PARENT_ID, Parent.Depth + 1 AS Depth,
CONVERT(varchar(255), Parent.Sort + ' | ' + CT.[NAME]) AS Sort
FROM Category CT
INNER JOIN Tree as Parent ON Parent.ID = CT.PARENT_ID
)
-- HERE IS YOUR TREE, Depths gives you the level starting with 0 and Sort is the Name based path
SELECT ID, [NAME], PARENT_ID, Depth, Sort FROM Tree
GO
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With