Questions tagged [recursive]
Using recursion to solve database problems.
262 questions
1
vote
2
answers
46
views
How to convert a recursive query to a function?
I have written a PostgreSQL query that's working perfectly:
WITH RECURSIVE x AS (
SELECT i, parent, id, name, type, '' AS path
FROM entry
WHERE name = 'JS-VBNET-2'
UNION ALL
SELECT e.i,...
0
votes
1
answer
16
views
How to fuzzy query a directory structure in PostgreSQL?
I was able to put together a rough idea for a PostgreSQL query to query over a node table, which contains id, parent__id, slug, and file_url (optional). It's considered a file if it has file_url, ...
- 221
0
votes
1
answer
57
views
T-SQL how to dynamically Pivot a tree
I've got a simple parent-child tree relationship that was built recursively
Parent
Child
A
B
B
E
B
C
E
NULL
C
NULL
A
F
F
NULL
this table comes from a recursive CTE:
with tree(parent, child) ...
- 117
0
votes
1
answer
61
views
PostgreSQL CTE Recursion - How to Improve Performance for Parent->Child Tree (8 levels deep, 890 roots)
I am working on a query that performs PostgreSQL CTE Recursion in PostgreSQL 13. This query is intended to recurse from the root nodes to the deepest leaf node with certain properties (labeled 'begat'...
- 50
2
votes
1
answer
79
views
Recursively sum child's nominal to parent, on dynamic level parent-child structure
i have data look like this :
i try to sum the Nominal column to each respective parent, so it will looks like this :
i provided the sql script for the data :
SET ANSI_NULLS ON
GO
SET ...
0
votes
1
answer
36
views
Designing a data model to handle both recurrence and nested dependencies
I'm building a web application that involves both recurrence and nested dependencies, and I'm struggling to pin down the appropriate data model.
The problem that the application aims to solve is: we ...
- 101
0
votes
1
answer
79
views
When generating combinations using a CTE, is there a way to use an index to group the elements of each combination?
I have a project that involves combining a variety of things into their possible combinations. This includes permutations, combinations, with and without repetition, and some more exotic ways of ...
- 439
0
votes
1
answer
182
views
What is the best way in Postgres to inherit values from parent row recursively if not provided?
Is there a pattern in SQL where a child row inherits empty (null?) values from a parent?
E.g., given the following 'chickens' table (sorry):
id
parent_id
name
flys
noise
weight
egg_color
...
- 101
0
votes
0
answers
171
views
Recursive CTE hiearchy snowflake -- join/ expand outward (columns) instead of rows?
I'm doing a dependency mapping explosion (like parts explosion).
I did a typical recursive CTE with a union all.
It looks like
with CTE as
( select abc from myTable where start_point = X
union all
...
- 1,709
0
votes
1
answer
215
views
Convert numbers to words | Spell out DECIMAL USD 1259.75 as 'One thousand two hundred fifty-nine dollars and seventy-five cents'
ALTER FUNCTION [dbo].[NumberToWords](@Number DECIMAL(18, 2))
RETURNS NVARCHAR(MAX)
AS
BEGIN
DECLARE @Words NVARCHAR(MAX)
SELECT @Words =
COALESCE(@Words + ' ', '') +
CASE
WHEN @...
- 25
1
vote
2
answers
547
views
How can I optimize a recursive CTE inside a IVTF?
I have a recursive CTE inside a inline table-valued function. The ITVF is returning a list of IDs containing a long sequence of ancestors for a person, it usually loops back about 12 to 18 times ...
- 121
0
votes
0
answers
35
views
How to match rows from relationship via a recursive CTE
Apologies for the terrible question title, I couldn't think how to describe this question in a single line.
I have a schema that looks roughly like this: https://dbdiagram.io/d/...
- 163
3
votes
2
answers
298
views
How to sum up the distinct Total Time of an Event ignoring duplicate overlaps in Times?
I have the following EventTimes table:
DROP TABLE IF EXISTS dbo.EventTimes;
CREATE TABLE dbo.EventTimes
(
EventTimeKeyId INT IDENTITY(1,1) PRIMARY KEY,
EventId INT NOT NULL,
StartTime TIME NOT ...
- 39.5k
0
votes
1
answer
155
views
SQL Pattern to get "root/ start" of uneven hierarchy dataset
I feel this is a common problem and I've seen it in some SQL challenges even but for the life of me, cannot think clearly about a solution.
Say you have an uneven hierarchy. Elements that belong to ...
- 1,709
2
votes
0
answers
23
views
Find best intersect (most elements) between Order (haystack) and Pricerules (needle)
Full disclosure
I have posted a greater scoped question at SO a couple of days ago with a bounty (no answers yet).
Scope here
How can a CTE be used to find a match with the most elements?
For the ...
- 219
1
vote
1
answer
114
views
PostgreSQL recursive query performance improvement
I'm building a database which is used to derive hierarchical relations for which I chose a PostgreSQL recursive CTE .
my table structure is
table_name |column_name |data_type ...
- 13
-1
votes
1
answer
81
views
My recursive query runs with no end in sight. Any idea as to how to solve this?
With A as(
select client_id, convert(date,admission_date) start_date,
year(convert(date,admission_date)) start_year,
month(convert(date, admission_date)) start_month
from ...
- 21
-2
votes
1
answer
211
views
I want to make a tree of parents only in sql server
My table in the database
How can I get my result as Where child = 'chl1'?
0
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1
answer
532
views
How can I recursively query a table containing LTREE to get the tree like structure when some of the parent paths are missing?
Lets say I have this table:
CREATE TABLE nodes (node_path ltree);
INSERT INTO nodes VALUES ('Top.Science');
INSERT INTO nodes VALUES ('Top.Science.Astronomy.Astrophysics');
INSERT INTO nodes VALUES ('...
1
vote
0
answers
318
views
Is it possible to limit infinte recursion in an Oracle CTE?
In a DBMS like Microsoft SQL, there is a default limit of 100 recursions, in a recursive CTE, which can be adjusted with:
WITH cte AS (
…
)
SELECT * FROM cte OPTION (MAXRECURSION …);
As far as I ...
- 2,919
0
votes
1
answer
241
views
"ON UPDATE" in self referencing table
I have a table Category with a parent_id column referencing the self id column, for this, I used "ON DELETE CASCADE" meaning if the parent is deleted, other children would be deleted too.
At ...
- 23
1
vote
0
answers
126
views
Mysql8 Unable to order the result of WITH RECURSIVE query
I am using the WITH RECURSIVE query to generate a hierarchy of users. The data and the query used is shared in https://www.db-fiddle.com/f/oTbCcMQb5a4B6V96DAYJHG/0 . The query is returning the results ...
- 121
8
votes
2
answers
679
views
How can I efficiently traverse graph data with this pattern?
I have some relations embodying a directed acyclic graph that includes patterns similar to the following:
I'm looking for an efficient way to traverse this graph data. Here is an example of the ...
- 439
0
votes
0
answers
3k
views
How to fix error "Line 25: The statement terminated. The maximum recursion 100 has been exhausted before statement completion."
I added OPTION (MAXRECURSION 1000) at the very bottom but it was not enough. My query:
Use DatabaseName;
DECLARE @SOURCE_TABLE_NAME NVARCHAR(200) = 'WorkOrderVersion'
DECLARE @SOURCE_SCHEMA_NAME ...
- 1
1
vote
0
answers
212
views
How to write query to link complex Parent-Child relationships
We have a table that has a DefectID field, and a PreviousDefectID field, in order to link defect records to each other as they change through time.
I need to link these fields together by creating a ...
- 11
8
votes
1
answer
623
views
Schema-binding with recursive scalar UDF
TL;DR; Is it a bug that SQL Server allows a scalar UDF to recursively call itself when schema-bound, but only when altered to do so using the CREATE OR ALTER syntax? Or is it a bug that other syntaxes ...
- 14.4k
3
votes
2
answers
891
views
From last id, recursively find parent id and fill column
CREATE TABLE t1
(
COL1 nvarchar(36),
COL2 nvarchar(36),
ExpectedResult nvarchar(36)
)
INSERT INTO t1 (COL1, COL2, ExpectedResult)
VALUES
('CA4462D3-BD2C-4C80-A50E-586DA28A877A','CA4462D3-BD2C-4C80-...
- 33
3
votes
1
answer
356
views
Return recursive self joins in PostgreSQL with aggregated data
I have this simple table schema:
SQL Fiddle
PostgreSQL 9.6 Schema Setup:
CREATE TABLE IF NOT EXISTS users(
id INT NOT NULL PRIMARY KEY, email TEXT NOT NULL UNIQUE,
password TEXT NOT NULL, ...
- 165
0
votes
1
answer
821
views
MySQL Select query for a calculated column that uses previous row value for current row
I am stuck at this. Trying to help PM team to translate a calculation from Excel using a MySQL select query to do reporting. Your help is appreciated.
Table has 3 columns - Employee, Month, Salary. ...
- 1
0
votes
1
answer
214
views
Why PostgreSQL RECURSIVE query iteration does not return the same result as manually created one?
I have the following test table:
SELECT * FROM attempts order by id;
id | user_id | name
----+---------+------
1 | 1 | a
2 | 2 | b
3 | 1 | b
4 | 1 | c
5 | 2 | ...
- 121
1
vote
2
answers
554
views
How does PostgreSQL recursive query treat SELECT MIN(ID) FROM T on each iteration?
I have the following query that I do not understand how it works, especially the subquery that returns the minimum ID without grouping.
WITH RECURSIVE t(id, user_id, name) AS (
select min(id) - 1, ...
- 121
0
votes
0
answers
225
views
Make this recursive CTE more dynamic
I have this script that enables me to extract hierarchies and the description for each level however the number of levels has to be known beforehand to define the number of select queries necessary ...
- 1
1
vote
0
answers
50
views
Recursive CTE get
I have the following tables:
Table1
id
entity_id
value
Table2 - Same structure as Table1
id
entity_id
value
Table3
source_id
destination_id
entity_id
Table1 and Table2 are both partitions from ...
- 11
0
votes
1
answer
281
views
How does SQL Server know not to execute Anchor element in Recursion CTE for 2nd Iteration / 1st Recursion?
I've been reading up on the inner workings of CTE Recursion and I'm still not quite sure how SQL Server is implementing the Anchor element in their source code and how SQL Server Query Execution ...
- 275
0
votes
0
answers
235
views
Optimising a recursive SQL query that processes several million records in BQ
I need help optimizing a recursive SQL query in BQ.
I have hierarchical data stored in a table as parent-child relationships, i.e
will be stored as
parent_item_id
child_item_id
1
1
1
2
1
3
3
4
...
- 101
0
votes
0
answers
173
views
How to use variable in the select query PostgreSQL
I'm looking for a way to write a recursive query, but I'm getting an error.
"SQL Error [42601]: ERROR: syntax error at or near "with recursive"
Position: 287"
query result "...
- 1
1
vote
1
answer
1k
views
How to find child and grandchildren tables of a main table by order
I have this script to return all child and grandchildren tables with their level from a database . How do I change this if I only want to return the child and grandchildren tables of a particular ...
- 67
3
votes
1
answer
318
views
String Manipulation of the Result from Recursive CTE
Good afternoon everyone
I found just one post here within the last year about this, but it doesn't help my situation.
I have been working with MySQL and trying to improve my knowledge of recursive CTE....
- 33
0
votes
1
answer
388
views
Generate hierarchical structure in sql server
I have a table employees
id
name
manager
1
susan
null
2
john
1
3
mary
1
4
josh
3
5
mathew
4
6
leo
2
7
peter
5
I want an output like:
id
name
hierarchy
1
susan
null
2
john
susan->john
3
...
- 183
1
vote
1
answer
2k
views
Generate dates using recursive cte
I have a table sales
product_id period_start period_end sale
----------------------------------------
1 2019-01-25 2019-02-28 100
2 2018-12-01 2020-01-01 10
3 ...
- 183
4
votes
1
answer
77
views
best practice for dependency roots
When a database has a dependency table showing the parent-child relationship of items...
I've mostly seen guides that assume the top level parent has a "parent id" field which is either zero ...
- 41
1
vote
1
answer
1k
views
Why does a Postgres recursive CTE need the list of columns as argument?
This is kind of a subjective question.
If I have a recursive CTE something like:
WITH RECURSIVE r(x, y) AS ( ...
SELECT x, y -- select1
FROM t WHERE ..
UNION
SELECT t.x, t.y -- ...
- 813
2
votes
0
answers
180
views
Problem with sysdepends while checking dependencies
I have this script to list all dependencies of all views in a database . I get the dependencies in the right order when I use sysdepends ,but I am missing a few dependencies while using sysdepends. ...
- 99
0
votes
1
answer
43
views
Retreive upper heirarchy
I have Categories stored in a single table.
id name parentId path
A1 Cat 1 0 Cat 1
A2 Cat 2 A1 Cat 1 > Cat 2
A3 Cat 3 A2 Cat 1 > Cat 2 > Cat 3
...
- 103
0
votes
1
answer
1k
views
How can I handle cycles / infinite loops in recursive CTEs in MySQL
Cycles in graphs lead to infinite loops in CTEs.
Dealing with them in Postgres is straightforward.
Since 8.0 MySQL also allows for CTEs. How I can detect cycles and infinite loops in MySQL CTEs?
The ...
- 813
0
votes
1
answer
278
views
Retrieve all linked categories
I have Categories stored in a single table.
Where there is no limit on number of childerns.
I want to fetch all the linked categories for the provided category id:
The reason for getting the hierarchy ...
- 103
1
vote
0
answers
62
views
TSQL - retrieve all IDs in a tree for a given subnode
I've tried to translate and implement the PostGres solution to the problem found here: PostgreSQL - retrieve all IDs in a tree for a given subnode, but I'm either programming it wrong, or ...
- 111
3
votes
1
answer
2k
views
Concatenate all previous row values from a TEXT column in reverse order
My Postgres version is 11.15. I have a table like:
id
employee
1
Anna
2
Bill
3
Carol
4
Dave
5
Tom
The output I need is
id
cumulative_employees
1
Anna
2
Bill, Anna
3
Carol, Bill, Anna
4
...
0
votes
0
answers
384
views
How to optimize (or get an alternative faster solution to) this recursive query that groups using recursive CTEs in Postgres?
I am on the quest to implement an NMS filter for labels in a Database.
For context, here's a link to my first question, where I explain what NMS is and what I'm trying to achieve (I will edit that ...
- 51
1
vote
3
answers
226
views
Finding the Second (time) Interval within X of the current time
I have a need to find, for a given current second and upper and lower boundary, find all of the seconds that would fall within that, wrapping at the 59 second mark.
With that word salad out of the way,...
- 9,244