I have a table called AccountNode.
Where the the column nodeId has a parent in the ParentNodeId col.
AccountNode
nodeId | ParentNodeId | Flag | SetId |
1 2 N 1
2 115 N 1
115 4 N 1
4 5 Y 1
12 13 N 1
13 14 N 1
14 15 Y 1
23 24 N 1
25 30 Y 1
What i need :
i need to get the parent node of each node id where the flag is Y (this is where we need to stop our recursive cte), for the setId passed as parameter to the procedure.
eg :
input:
for set_id : 1
output:
nodeId parentNode flag set_id
1 5 Y 1
12 15 Y 1
25 30 Y 1
i have written a recursive cte to get the parent node for a node id , but i am having trouble wrting it for a setid where
, i need to loop through all the nodeIds in a setid , to get the parentNode.
Here is my sql :
with accountNode_cte (nodeId, parentNode, flag, set_id) as
(select nodeId , parentNode, flag, set_id) from accountNode where nodeId = '1'
union all
select accountNode.nodeId, accountNode.parentNode, accountNode.flag, accountNode.set_id from
accountNode
join accountNode_cte on accountNode.nodeId = accountNode_cte.parentNode
and accountNode_cte.flag !='Y')
select * from accountNode_cte where flag='Y'
i am pretty new to writing sql procedures , not sure how to go about this
Traverse the node hierarchy from the starting nodes, remember starting point, track level, take max within starting point level rows.
with accountNode_cte(p, l, nodeId, parentNode, flag, set_id) as (
select parentNodeId p, 1 l, nodeId , parentNodeId, flag, set_id
from accountNode
where flag = 'Y' and set_id = 1
union all
select p, l+1, accountNode.nodeId, accountNode.parentNodeId, accountNode.flag, accountNode.set_id
from accountNode
join accountNode_cte on accountNode.parentnodeId = accountNode_cte.NodeId
)
select distinct first_value(nodeId) over(partition by p order by l desc) nodeId, p parentnId
from accountNode_cte;
db<>fiddle
Related
In SQL Server 2016, I have a table with the following chaining structure:
dbo.Item
OriginalItem
ItemID
NULL
7
1
2
NULL
1
5
6
3
4
NULL
8
NULL
5
9
11
2
3
EDIT NOTE: Bold numbers were added as a response to #lemon comments below
Importantly, this example is a trivialized version of the real data, and the neatly ascending entries is not something that is present in the actual data, I'm just doing that to simplify the understanding.
I've constructed a query to get what I'm calling the TerminalItemID, which in this example case is ItemID 4, 6, and 7, and populated that into a temporary table #TerminalItems, the resultset of which would look like:
#TerminalItems
TerminalItemID
4
6
7
8
11
What I need, is a final mapping table that would look something like this (using the above example -- note that it also contains for 4, 6, and 7 mapping to themselves, this is needed by the business logic):
#Mapping
ItemID
TerminalItemID
1
4
2
4
3
4
4
4
5
6
6
6
7
7
8
8
9
11
11
11
What I need help with is how to build this last #Mapping table. Any assistance in this direction is greatly appreciated!
This should do:
with MyTbl as (
select *
from (values
(NULL, 1 )
,(1, 2 )
,(2, 3 )
,(3, 4 )
,(NULL, 5 )
,(5, 6 )
,(NULL, 7 )
) T(OriginalItem, ItemID)
)
, TerminalItems as (
/* Find all leaf level items: those not appearing under OriginalItem column */
select LeafItem=ItemId, ImmediateOriginalItem=M.OriginalItem
from MyTbl M
where M.ItemId not in
(select distinct OriginalItem
from MyTbl AllParn
where OriginalItem is not null
)
), AllLevels as (
/* Use a recursive CTE to find and report all parents */
select ThisItem=LeafItem, ParentItem=ImmediateOriginalItem
from TerminalItems
union all
select ThisItem=AL.ThisItem, M.OriginalItem
from AllLevels AL
inner join
MyTbl M
on M.ItemId=AL.ParentItem
)
select ItemId=coalesce(ParentItem,ThisItem), TerminalItemId=ThisItem
from AllLevels
order by 1,2
Beware of the MAXRECURSION setting; by default SQLServer iterates through recursion 100 times; this would mean that the depth of your tree can be 100, max (the maximum number of nodes between a terminal item and its ultimate original item). This can be increased by OPTION(MAXRECURSION nnn) where nnn can be adjusted as needed. It can also be removed entirely by using 0 but this is not recommended because your data can cause infinite loops.
This is a typical gaps-and-islands problem and can also be carried out without recursion in three steps:
assign 1 at the beginning of each partition
compute a running sum over your flag value (generated at step 1)
extract the max "ItemID" on your partition (generated at step 2)
WITH cte1 AS (
SELECT *, CASE WHEN OriginalItem IS NULL THEN 1 ELSE 0 END AS changepartition
FROM Item
), cte2 AS (
SELECT *, SUM(changepartition) OVER(ORDER BY ItemID) AS parts
FROM cte1
)
SELECT ItemID, MAX(ItemID) OVER(PARTITION BY parts) AS TerminalItemID
FROM cte2
Check the demo here.
Assumption: Your terminal id items correspond to the "ItemID" value preceding a NULL "OriginalItem" value.
EDIT: "Fixing orphaned records."
The query works correctly when records are not orphaned. The only way to deal them, is to get missing records back, so that the query can work correctly on the full data.
This is carried out by an extra subquery (done at the beginning), that will apply a UNION ALL between:
the available records of the original table
the missing records
WITH fix_orphaned_records AS(
SELECT * FROM Item
UNION ALL
SELECT NULL AS OriginalItem,
i1.OriginalItem AS ItemID
FROM Item i1
LEFT JOIN Item i2 ON i1.OriginalItem = i2.ItemID
WHERE i1.OriginalItem IS NOT NULL AND i2.ItemID IS NULL
), cte AS (
...
Missing records correspond to "OriginalItem" values that are never found within the "ItemID" field. A self left join will uncover these missing records.
Check the demo here.
You can use a recursive CTE to compute the last item in the sequence. For example:
with
n (orig_id, curr_id, lvl) as (
select itemid, itemid, 1 from item
union all
select n.orig_id, i.itemid, n.lvl + 1
from n
join item i on i.originalitem = n.curr_id
)
select *
from (
select *, row_number() over(partition by orig_id order by lvl desc) as rn from n
) x
where rn = 1
Result:
orig_id curr_id lvl rn
-------- -------- ---- --
1 4 4 1
2 4 3 1
3 4 2 1
4 4 1 1
5 6 2 1
6 6 1 1
7 7 1 1
See running example at db<>fiddle.
Let's suppose that I have this simple table:
ID
1
2
3
4
If I do:
WITH example AS
(
SELECT UNNEST(ARRAY[1,2,3,4]) as ID
)
SELECT ID, lAG(ID,1) over() as LAG_ID
FROM example
-- The shift is 1 in this case, but could be any integer in practice.
I got:
ID
LAG_ID
1
2
1
3
2
4
3
But I need a circular shift:
ID
LAG_ID
1
4
2
1
3
2
4
3
Is there an elegant way to produce this result ?
If ID is not nullable
WITH example AS
(
SELECT UNNEST(ARRAY[1,2,3,4]) as ID
)
SELECT ID, coalesce(lAG(ID,1) over(order by ID asc), (select max(ID) from example)) as LAG_ID
FROM example
A few days ago I installed DB2 LUW (11.5) on a server to play around with.
Now I would like to do some recursive SQL (Recursive Common Table Expression):
Let me show how I setup :
drop table relations;
create table relations (id int, parent int);
insert into relations values(0,NULL);
insert into relations values(1,0);
insert into relations values(2,1);
insert into relations values(3,1);
insert into relations values(4,3);
insert into relations values(5,0);
insert into relations values(6,5);
insert into relations values(7,5);
insert into relations values(8,6);
insert into relations values(9,7);
insert into relations values(10,0);
insert into relations values(11,1);
commit;
Now I would like to see the hierarchy in the table. So I tried the following:
with recur(id, parent, level) as
(
select rel.id id, rel.parent parent, 0 level from relations rel where rel.id=0
union all
select rel.id, rel.parent, rec.level+1 from recur rec, relations rel where rec.id=rel.parent
and rec.level<10
)
select id, lpad(parent, level*2, ' ') from recur;
This gives me:
ID PARENT
----------- ------------------
0 -
1 0
5 0
10 0
2 1
3 1
11 1
6 5
7 5
4 3
8 6
9 7
This is (to me) : "Search Breadth First"
What I would like to see is "Search Depth First"
So I did this:
with recur(id, parent, level) as
(
select rel.id id, rel.parent parent, 0 level from relations rel where rel.id=0
union all
select rel.id, rel.parent, rec.level+1 from recur rec, relations rel where rec.id=rel.parent
and rec.level<10
)
search depth first by parent set ord
select id, lpad(parent, level*2, ' ') parent from recur order by ord;
But this delivers to me:
SQL0104N An unexpected token "search depth first by parent set ord sel" was
found following "t and rec.level<10 )". Expected tokens may include:
"<values>". SQLSTATE=42601
No clue how to solve it now. I (think I) have tried a lot of possible solutions. But none worked.
I'm starting to believe that DB2 LUW (11.5) doesn't know about Search Depth First. Or some setting must be made to make DB2 aware of the "SDF" possibility.
My question to you all:
How to solve this problem? How do I get Search Depth First to work?
On the positive....following works like a charms....but that is not whatI want tot know :-)
select id, lpad(parent, level*2, ' ') parent, level
from relations
start with id=0
connect by prior id=parent;
ID PARENT LEVEL
----------- ---------- -----------
0 - 1
1 0 2
2 1 3
3 1 3
4 3 4
11 1 3
5 0 2
6 5 3
8 6 4
7 5 3
9 7 4
10 0 2
This works like a charm, but I had tot make a switch in the database (and a restart):
db2set DB2_COMPATIBILITY_VECTOR=08
Your question is about displaying rows in a specific ordering, not about searching in a specific ordering.
You can display the rows in the ordering you want by assembling an ordering column that fits your needs.
For example:
with
n (id, parent, lvl, ordering) as (
select id, parent, 1, lpad(id, 3, '0') || lpad('', 30, ' ')
from relations
where parent is null
union all
select r.id, r.parent, n.lvl + 1, trim(n.ordering) || '/' || lpad(r.id, 3, '0')
from n, relations r where r.parent = n.id
)
select id, lpad(parent, lvl * 2, ' ') as parent, lvl
from n
order by ordering;
Result:
ID PARENT LVL
--- --------- ---
0 1
1 0 2
2 1 3
3 1 3
4 3 4
11 1 3
5 0 2
6 5 3
8 6 4
7 5 3
9 7 4
10 0 2
See running example at db<>fiddle.
I want to return all possible combinations of values in a column by means of two new columns. E.g. my column consists out of the values (A,B,C,D). The possible combinations of those values are (A,B), (A,C), (A,D), (B,C), (B,D), (C,D), (A,B,C), (B,D,C), (D,C,A), (C,A,B) [Remark: I don't want to consider (1) the combintions with just one value, (2) the combination with all values and (3) the combination with no values. Thus I have 2^(n)-n-1-1 combinations for n different values]. I want to list all those combinations in two columns like demonstrated below.
Consider that I start with this column:
Col0
----
A
B
C
D
Out of Col0 I want to produce the 10 combinations using two columns:
Col1 Col2
---- ----
1 A
1 B
2 A
2 C
3 A
3 D
4 B
4 C
5 B
5 D
6 C
6 C
7 A
7 B
7 C
8 B
8 C
8 D
9 C
9 D
9 A
10 D
10 A
10 B
How do I do this in SQL? I use SQLite.
Thank you a lot!
I have a solution, but it requires two changes...
Each item must be given an id (starting from 1)
The output id's may not be sequential
id | datum
----+-------
1 | A
2 | B
3 | C
4 | D
(The output id's I calculate are effectively identifiers for each Permutation, but I don't output permutations you're not interested in...)
group_id | datum
----------+-------
6 | A
6 | B
7 | A
7 | C
8 | A
8 | D
12 | B
12 | C
13 | B
13 | D
18 | C
18 | D
32 | A
32 | B
32 | C
33 | A
33 | B
33 | D
38 | A
38 | C
38 | D
63 | B
63 | C
63 | D
http://dbfiddle.uk/?rdbms=sqlite_3.8&fiddle=87d670ecaba8b735cb3f95fa66cea96b
http://dbfiddle.uk/?rdbms=sqlite_3.8&fiddle=26e4f59874009ef95367d85565563c3c
WITH
cascade AS
(
SELECT
1 AS depth,
NULL AS parent_id,
id,
datum,
id AS datum_id
FROM
sample
UNION ALL
SELECT
parent.depth + 1,
parent.id,
parent.id * (SELECT MAX(id)+1 FROM sample) + child.id - 1,
child.datum,
child.id
FROM
cascade AS parent
INNER JOIN
sample AS child
ON child.id > parent.datum_id
),
travelled AS
(
SELECT
depth AS depth,
parent_id AS parent_id,
id AS group_id,
datum AS datum,
datum_id AS datum_id
FROM
cascade
WHERE
depth NOT IN (1, (SELECT COUNT(*) FROM sample))
UNION ALL
SELECT
parent.depth,
parent.parent_id,
child.group_id,
parent.datum,
parent.datum_id
FROM
travelled AS child
INNER JOIN
cascade AS parent
ON parent.id = child.parent_id
)
SELECT
group_id,
datum
FROM
travelled
ORDER BY
group_id,
datum_id
The first CTE walks all the available combinations (recursively) creating a directed graph. At this stage I don't exclude combinations of one item, or all items, but I do exclude equivalent permutations.
Each node also has a unique identifier calculated for it. There are gaps in these ids, because the calculation would also work for all permutations, even though they're not all included.
Taking any node in that graph and walking up to the final parent node (recursively again) will always give a different combination than if you started from a different node in the graph.
So the second CTE does all of those walks, excluding the combinations of "just one item" and "all items".
The final select just outputs the results in order.
The gaps in the id's are probably avoidable but the maths is too hard for my head at the end of a working day.
The idea is to enumerate the power set, by assigning each value a power of 2, then iterate from 1 to 2^n - 1 , and filter the elements which corresponding bit is set.
-- map each value with a power of 2 : 1, 2, 4, 8, 16
with recursive ELEMENTS(IDX, POW, VAL) as (
-- init with dummy values
values(-1, 0.5, null)
union all
select IDX + 1,
POW * 2,
-- index the ordered values from 0 to N - 1
( select COL0
from DATA d1
where (select count(*) from DATA d2 where d2.COL0 < d1.COL0) = IDX + 1)
from ELEMENTS
where IDX + 1 < (select count(*) from data)
), POWER_SETS(ITER, VAL, POW) as (
select 1, VAL, POW from ELEMENTS where VAL is not null
union all
select ITER + 1, VAL, POW
from POWER_SETS
where ITER < (select SUM(POW) from elements) )
select ITER, VAL from POWER_SETS
-- only if the value's bit is set
where ITER & POW != 0
EDIT: 2nd version, with help from MatBailie. Only one of the CTE is recursive, and singleton subsets are excluded.
WITH RECURSIVE
-- number the values
elements(val, idx) AS (
SELECT d1.col0, (select count(*) from DATA d2 where d2.COL0 < d1.COL0)
FROM DATA d1
),
-- iterate from 3 (1 and 2 are singletons)
-- to 2^n - 1 (subset containing all the elements)
subsets(iter) AS (
VALUES(3)
UNION ALL
SELECT iter + 1
from subsets
WHERE iter < (1 << (SELECT COUNT(*) FROM elements)) - 1
)
SELECT iter AS Col1, val AS Col2
FROM elements
CROSS JOIN subsets
-- the element is present is this subset (the bit is set)
WHERE iter & (1 << idx) != 0
-- exclude singletons (another idea from MatBailie)
AND iter != (iter & -iter)
ORDER BY iter, val
If window functions and CTE is available then you can use the following approach
with data_rn as
(
select d1.col0 col1,
d2.col0 col2,
row_number() over (order by d1.col0) rn
from data d1
inner join data d2 on d1.col0 > d2.col0
)
select rn, col1 from data_rn
union all
select rn, col2 from data_rn
order by rn
dbfiddle demo
I have a table with such rows:
ID Parent_ID Name
1 (null) A
2 1 B
3 1 C
4 2 D
5 3 E
6 5 F
7 (null) G
8 (null) H
I need to get IDs of all related rows no matter if Name='A' or 'F' is passed as criteria. In this case I should receive all ID beside 7 and 8.
I tried lot of examples and read a lot of articles but I give up now. Can you help with it?
with
t as (
select id
from your_table
where name = 'D' -- your starting point
)
select id
from (
select id, parent_id from your_table
where parent_id is not null
union all
select parent_id, id from your_table
where parent_id is not null
union all
select id, null from t
)
start with parent_id is null
connect by nocycle prior id = parent_id
fiddle
A is at the root of a hierarchy (it's the parent of B, which is the parent of D, etc.). To start with A and work down to F (and also down to D and E, which also have A as a parent through different routes):
SELECT ID, Parent_ID, Name
FROM tbl
START WITH Name = 'A'
CONNECT BY PRIOR ID = Parent_ID
F is at the end of a hierarchy. Oracle calls this a "leaf". To start with leaf F and work up to A at the top:
SELECT ID, Parent_ID, Name
FROM tbl
START WITH Name = 'F' -- start with F instead of A
CONNECT BY PRIOR Parent_ID = ID -- switch the CONNECT BY to work up
Oracle has a SYS_CONNECT_BY_PATH function that's great for visualizing the hierarchy. Here's how to use it in the first query (A down to F):
SELECT ID, Parent_ID, Name, SYS_CONNECT_BY_PATH(Name, '/') AS Path
FROM tbl
START WITH Name = 'A'
CONNECT BY PRIOR ID = Parent_ID
Results:
ID PARENT_ID NAME PATH
---- ---------- ---- -----------
1 A /A
2 1 B /A/B
4 2 D /A/B/D
3 1 C /A/C
5 3 E /A/C/E
6 5 F /A/C/E/F
You can use any delimeter you want as the second argument to SYS_CONNECT_BY_PATH.