Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Users Search
Help Dashboard Sign In Sign Up
Q&A Code Reviews Meta
Q&A
Posts Tags Edits
Ask Question

Welcome to Software Development on Codidact!

Will you help us build our independent community of developers helping developers? We're small and trying to grow. We welcome questions about all aspects of software development, from design to code to QA and more. Got questions? Got answers? Got code you'd like someone to review? Please join us.

Post History

77%
+5 −0
Q&A How to break infinite loop in CTE

I have a parent-child relation in my table, with possibly circular cases. Is it possible to break the infinite recursion in CTE checking values of all previous rows? I would need something like thi...

3 answers  ·  posted 3y ago by artaxerxe‭  ·  edited 7mo ago by Michael‭

Question sql sql-server common-table-expression
#7: Post edited by user avatar Michael‭ · 2024-04-05T10:25:04Z (7 months ago)
Fix table markdown 
How to break infinite loop in CTE
  • I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows? I would need something like this:
  • with my_cte(childId, parentId, col1)
  • AS (
  • SELECT r.childId, r.parentId, r.col1
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.childId, rel.parentId, rel.col1
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId, rel.parentId not in previous rows
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
  • Example table with records would be:
  • childId | parentId | col1
  • 1 | 3 | 1
  • 1 | 4 | 1
  • 3 | 5 | 1
  • 5 | 1 | 1 -- circular case
  • 6 | 2 | 1
  • 5 | 7 | 1
  • If I ask for hierarcy related to 1, I should get
  • childId | parentId | col1
  • 1 | 3 | 1
  • 1 | 4 | 1
  • 3 | 5 | 1
  • 5 | 1 | 1 -- circular case
  • 5 | 7 | 1
  • - 1 has two parents: 3 and 4.
  • - 3 has 1 parent: 5
  • - 5 has 2 parents: 1 and 7. But 1 brings the infinite loop, so the query should ignore this. And continue to the next row.
  • I have a parent-child relation in my table, with possibly circular cases. Is it possible to break the infinite recursion in CTE checking values of all previous rows? I would need something like this:
  • with my_cte(childId, parentId, col1)
  • AS (
  • SELECT r.childId, r.parentId, r.col1
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.childId, rel.parentId, rel.col1
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId, rel.parentId not in previous rows
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
  • Example table with records would be:
  • | childId | parentId | col1 |
  • |---------|----------|------|
  • | 1 | 3 | 1
  • | 1 | 4 | 1
  • | 3 | 5 | 1
  • | 5 | 1 | 1 -- circular case
  • | 6 | 2 | 1
  • | 5 | 7 | 1
  • If I ask for hierarchy related to 1, I should get
  • | childId | parentId | col1 |
  • |---------|----------|------|
  • | 1 | 3 | 1
  • | 1 | 4 | 1
  • | 3 | 5 | 1
  • | 5 | 1 | 1 -- circular case
  • | 5 | 7 | 1
  • - 1 has two parents: 3 and 4.
  • - 3 has 1 parent: 5
  • - 5 has 2 parents: 1 and 7. But 1 brings the infinite loop, so the query should ignore this. And continue to the next row.
sql sql-server common-table-expression
sql sql-server common-table-expression
#6: Post edited by user avatar Alexei‭ · 2024-04-04T07:46:28Z (7 months ago)
added the actual CTE tag
#5: Nominated for promotion by user avatar Alexei‭ · 2021-04-21T09:17:34Z (over 3 years ago)
#4: Post edited by user avatar artaxerxe‭ · 2021-04-19T13:16:37Z (over 3 years ago)
  • I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows? I would need something like this:
  • with my_cte(id, childId, parentId, col1, col2)
  • AS (
  • SELECT r.id, r.childId, r.parentId, r.col1, r.col2
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.id, rel.childId, rel.parentId, rel.col1, rel.col2
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId, rel.parentId not in previous rows
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
  • Example table with records would be:
  • id | childId | parentId | col1 | col2
  • 1 | 1 | 3 | 1 | null
  • 2 | 1 | 4 | 1 | null
  • 3 | 3 | 5 | 1 | null
  • 4 | 5 | 1 | 1 | null -- circular case
  • 5 | 6 | 2 | 1 | null
  • 6 | 5 | 7 | 1 | null
  • If I ask for hierarcy related to 1, I should get
  • id | childId | parentId | col1 | col2
  • 1 | 1 | 3 | 1 | null
  • 2 | 1 | 4 | 1 | null
  • 3 | 3 | 5 | 1 | null
  • 4 | 5 | 1 | 1 | null -- circular case
  • 6 | 5 | 7 | 1 | null
  • - 1 has two parents: 3 and 4.
  • - 3 has 1 parent: 5
  • - 5 has 2 parents: 1 and 7. But 1 brings the infinite loop, so the query should ignore this. And continue to the next row.
  • I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows? I would need something like this:
  • with my_cte(childId, parentId, col1)
  • AS (
  • SELECT r.childId, r.parentId, r.col1
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.childId, rel.parentId, rel.col1
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId, rel.parentId not in previous rows
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
  • Example table with records would be:
  • childId | parentId | col1
  • 1 | 3 | 1
  • 1 | 4 | 1
  • 3 | 5 | 1
  • 5 | 1 | 1 -- circular case
  • 6 | 2 | 1
  • 5 | 7 | 1
  • If I ask for hierarcy related to 1, I should get
  • childId | parentId | col1
  • 1 | 3 | 1
  • 1 | 4 | 1
  • 3 | 5 | 1
  • 5 | 1 | 1 -- circular case
  • 5 | 7 | 1
  • - 1 has two parents: 3 and 4.
  • - 3 has 1 parent: 5
  • - 5 has 2 parents: 1 and 7. But 1 brings the infinite loop, so the query should ignore this. And continue to the next row.
#3: Post edited by user avatar artaxerxe‭ · 2021-04-19T13:03:53Z (over 3 years ago)
  • I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows? I would need something like this:
  • with my_cte(id, childId, parentId, col1, col2)
  • AS (
  • SELECT r.id, r.childId, r.parentId, r.col1, r.col2
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.id, rel.childId, rel.parentId, rel.col1, rel.col2
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId, rel.parentId not in previous rows
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
  • I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows? I would need something like this:
  • with my_cte(id, childId, parentId, col1, col2)
  • AS (
  • SELECT r.id, r.childId, r.parentId, r.col1, r.col2
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.id, rel.childId, rel.parentId, rel.col1, rel.col2
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId, rel.parentId not in previous rows
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
  • Example table with records would be:
  • id | childId | parentId | col1 | col2
  • 1 | 1 | 3 | 1 | null
  • 2 | 1 | 4 | 1 | null
  • 3 | 3 | 5 | 1 | null
  • 4 | 5 | 1 | 1 | null -- circular case
  • 5 | 6 | 2 | 1 | null
  • 6 | 5 | 7 | 1 | null
  • If I ask for hierarcy related to 1, I should get
  • id | childId | parentId | col1 | col2
  • 1 | 1 | 3 | 1 | null
  • 2 | 1 | 4 | 1 | null
  • 3 | 3 | 5 | 1 | null
  • 4 | 5 | 1 | 1 | null -- circular case
  • 6 | 5 | 7 | 1 | null
  • - 1 has two parents: 3 and 4.
  • - 3 has 1 parent: 5
  • - 5 has 2 parents: 1 and 7. But 1 brings the infinite loop, so the query should ignore this. And continue to the next row.
#2: Post edited by user avatar artaxerxe‭ · 2021-04-19T12:53:39Z (over 3 years ago)
  • I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows. I would need something like this:
  • with my_cte(id, childId, parentId, col1, col2)
  • AS (
  • SELECT r.id, r.childId, r.parentId, r.col1, r.col2
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.id, rel.childId, rel.parentId, rel.col1, rel.col2
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId not in previous rel.childId
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
  • I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows? I would need something like this:
  • with my_cte(id, childId, parentId, col1, col2)
  • AS (
  • SELECT r.id, r.childId, r.parentId, r.col1, r.col2
  • FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
  • UNION ALL
  • SELECT rel.id, rel.childId, rel.parentId, rel.col1, rel.col2
  • FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
  • -- check that rel.childId, rel.parentId not in previous rows
  • )
  • SELECT DISTINCT * from shared_documents
  • How can I achieve this? Or how to approach this?
#1: Initial revision by user avatar artaxerxe‭ · 2021-04-19T12:40:13Z (over 3 years ago) 
How to break infinite loop in CTE
I have a parent child relation in my table, with possibly circular cases. Is it possible to break the infinite recursivity in CTE checking values of all previous rows. I would need something like this:

    with my_cte(id, childId, parentId, col1, col2)
    AS (
    SELECT r.id, r.childId, r.parentId, r.col1, r.col2
	FROM My_Table r WHERE r.childId = 'x' AND (r.col1 = 1 or r.col1 = 2)
	UNION ALL 
	SELECT rel.id, rel.childId, rel.parentId, rel.col1, rel.col2
		FROM My_Table rel INNER JOIN my_cte sd ON rel.childId = sd.parentId where (rel.col1 = 1 OR rel.col1 = 2) AND ...
    -- check that rel.childId not in previous rel.childId
    )
    SELECT DISTINCT * from shared_documents

How can I achieve this? Or how to approach this?
sql sql-server common-table-expression