SQL query to get Groups and sub groups hierarchy - sql-server

Question

Account table
ac_id ac_name st_id
----------- ------------- -----------
1 LIABILITES 1
2 ASSET 1
3 REVENUE 1
4 EXPENSES 1
5 EQUITY 1
Groups table
grp_id grp_name ac_no grp_of st_id type_ cmp_id
----------- ------------------- ---------- -------- --------- --------- --------
1 Capital Account 1 0 1 0 0
2 Current Liability 1 0 1 0 0
3 Loan Liability 1 0 1 0 0
4 Suspense A/C 1 0 1 0 0
5 Current Assets 2 0 1 0 0
6 Fixed Assests 2 0 1 0 0
7 Investment 2 0 1 0 0
8 Misc. Expenses 2 0 1 0 0
9 Direct Income 3 0 1 0 0
10 Indirect Income 3 0 1 0 0
11 Sale Account 3 0 1 0 0
12 Direct Expense 4 0 1 0 0
13 Indirect Expense 4 0 1 0 0
14 Purchase Account 4 0 1 0 0
15 Sundry Creditors 2 1 1 0 0
16 Sundry Debitors 5 1 1 0 0
17 Bank Account 5 1 1 0 0
18 Cash In Hand 5 1 1 0 0
19 Duties & Taxes 2 1 1 0 0
20 Salary 12 1 1 0 0
21 Personal 5 1 1 0 0
22 Loan 2 0 1 0 0
23 Customer 16 1 1 0 0
34 Vendor 15 1 1 0 0
38 Sale Softwares 11 1 1 1 1
46 Stock In Hand 5 1 1 1 1
47 test 1 1 1 1 1
48 test in 47 1 1 1 1
Query to get all groups hierarchy.
declare #ac_no as int =2
;With CTE(grp_id,grp_name,ac_no,Level)
AS
( SELECT
grp_id,grp_name,ac_no,CAST(1 AS int)
FROM
Groups
WHERE
grp_id in (select grp_id from Groups where (ac_no=#ac_no) and grp_of=0)
UNION ALL
SELECT
o.grp_id,o.grp_name,o.ac_no,c.Level+1
FROM
Groups o
INNER JOIN
CTE c
ON c.grp_id=o.ac_no --where o.ac_no=2 and o.grp_of=1
)
select * from CTE
Result is ok for ac_no=2/3/4
grp_id grp_name ac_no Level
----------- ------------------- ----------- ------
5 Current Assets 2 1
6 Fixed Assests 2 1
7 Investment 2 1
8 Misc. Expenses 2 1
22 Loan 2 1
16 Sundry Debitors 5 2
17 Bank Account 5 2
18 Cash In Hand 5 2
21 Personal 5 2
46 Stock In Hand 5 2
23 Customer 16 3
But when I try to get result for ac_no=1;
I get error :
Msg 530, Level 16, State 1, Line 4
The statement terminated. The maximum recursion 100 has been exhausted before statement completion.

Answer 1

I think the issue is that you end up in an infinite recursion as you have a row that is it's own parent/child (eg. grp_id = ac_no).
I think it should work if you add a limiting clause to the recursive member like this:
DECLARE #ac_no AS int = 1;
WITH CTE (grp_id , grp_name , ac_no , Level ) AS (
SELECT grp_id, grp_name, ac_no, CAST( 1 AS int )
FROM Groups
WHERE grp_id IN (SELECT grp_id FROM Groups WHERE ac_no = #ac_no AND grp_of = 0)
UNION ALL
SELECT o.grp_id, o.grp_name, o.ac_no, c.Level + 1
FROM Groups o
INNER JOIN CTE c ON c.grp_id = o.ac_no --where o.ac_no=2 and o.grp_of=1
WHERE c.ac_no <> c.grp_id
)
SELECT * FROM CTE;