Question

I have a table Category with Parent and Child relations my table schema is below:

CategoryID       ParentID        CategoryName
1                  0                A
2                  1                B
3                  1                C
4                  2                D
5                  0                E
6                  5                F
7                  5                G
8                  6                I
9                  1                J
10                 0                L

Now When I want to select all categories which did not have the ParentId 1 and it’s Child CategoryID, my output should be look like below when I am passing CategoryID 1

CategoryID        ParentID        CategoryName
5                   0                  E
6                   5                  F
7                   5                  G
8                   6                  H
10                  0                  L

how I can find the results look like that.

Answer 1

The gist of this is to

1. select all records that descend from Category 1
2. exclude them from the final result

SQL Statement

;WITH q AS (
    SELECT  CategoryID, ParentID
    FROM    Category
    WHERE   CategoryID =1           
    UNION ALL
    SELECT  c.CategoryID, c.ParentID
    FROM    Category c
            INNER JOIN q ON q.CategoryID = c.ParentID
)
SELECT  *
FROM    Category c
WHERE   NOT EXISTS (SELECT CategoryID FROM q WHERE q.CategoryID = c.CategoryID)

Test data

;WITH Category (CategoryID, ParentID, CategoryName) AS (
    SELECT  1, 0, 'A'
    UNION ALL SELECT 2, 1, 'B'
    UNION ALL SELECT 3, 1, 'C'
    UNION ALL SELECT 4, 2, 'D'
    UNION ALL SELECT 5, 0, 'E'
    UNION ALL SELECT 6, 5, 'F'
    UNION ALL SELECT 7, 5, 'G'
    UNION ALL SELECT 8, 6, 'I'
    UNION ALL SELECT 9, 1, 'J'
    UNION ALL SELECT 10, 0, 'L'
)   
, q AS (
    SELECT  CategoryID, ParentID
    FROM    Category
    WHERE   CategoryID =1           
    UNION ALL
    SELECT  c.CategoryID, c.ParentID
    FROM    Category c
            INNER JOIN q ON q.CategoryID = c.ParentID
)
SELECT  *
FROM    Category c
WHERE   NOT EXISTS (SELECT CategoryID FROM q WHERE q.CategoryID = c.CategoryID)