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I have a simple categories table as with the following columns:
Id
Name
ParentId
So, an infinite amount of Categories can be the child of a category. Take for example the following hierarchy:
I want, in a simple query that returns the category "Business Laptops" to also return a column with all it's parents, comma separator or something:
Or take the following example:
Recursive cte to the rescue....
Create and populate sample table (Please save us this step in your future questions):
DECLARE #T as table
(
id int,
name varchar(100),
parent_id int
)
INSERT INTO #T VALUES
(1, 'A', NULL),
(2, 'A.1', 1),
(3, 'A.2', 1),
(4, 'A.1.1', 2),
(5, 'B', NULL),
(6, 'B.1', 5),
(7, 'B.1.1', 6),
(8, 'B.2', 5),
(9, 'A.1.1.1', 4),
(10, 'A.1.1.2', 4)
The cte:
;WITH CTE AS
(
SELECT id, name, name as path, parent_id
FROM #T
WHERE parent_id IS NULL
UNION ALL
SELECT t.id, t.name, cast(cte.path +','+ t.name as varchar(100)), t.parent_id
FROM #T t
INNER JOIN CTE ON t.parent_id = CTE.id
)
The query:
SELECT id, name, path
FROM CTE
Results:
id name path
1 A A
5 B B
6 B.1 B,B.1
8 B.2 B,B.2
7 B.1.1 B,B.1,B.1.1
2 A.1 A,A.1
3 A.2 A,A.2
4 A.1.1 A,A.1,A.1.1
9 A.1.1.1 A,A.1,A.1.1,A.1.1.1
10 A.1.1.2 A,A.1,A.1.1,A.1.1.2
See online demo on rextester
I have a simple categories table as with the following columns:
Id
Name
ParentId
So, an infinite amount of Categories can be the child of a category. Take for example the following hierarchy:
I want, in a simple query that returns the category "Business Laptops" to also return a column with all it's parents, comma separator or something:
Or take the following example:
Recursive cte to the rescue....
Create and populate sample table (Please save us this step in your future questions):
DECLARE #T as table
(
id int,
name varchar(100),
parent_id int
)
INSERT INTO #T VALUES
(1, 'A', NULL),
(2, 'A.1', 1),
(3, 'A.2', 1),
(4, 'A.1.1', 2),
(5, 'B', NULL),
(6, 'B.1', 5),
(7, 'B.1.1', 6),
(8, 'B.2', 5),
(9, 'A.1.1.1', 4),
(10, 'A.1.1.2', 4)
The cte:
;WITH CTE AS
(
SELECT id, name, name as path, parent_id
FROM #T
WHERE parent_id IS NULL
UNION ALL
SELECT t.id, t.name, cast(cte.path +','+ t.name as varchar(100)), t.parent_id
FROM #T t
INNER JOIN CTE ON t.parent_id = CTE.id
)
The query:
SELECT id, name, path
FROM CTE
Results:
id name path
1 A A
5 B B
6 B.1 B,B.1
8 B.2 B,B.2
7 B.1.1 B,B.1,B.1.1
2 A.1 A,A.1
3 A.2 A,A.2
4 A.1.1 A,A.1,A.1.1
9 A.1.1.1 A,A.1,A.1.1,A.1.1.1
10 A.1.1.2 A,A.1,A.1.1,A.1.1.2
See online demo on rextester
I have a matter which seemed simple to solve but now I find it troublesome.
In simplification - I need to find a way to identify unique sets of rows within groups defined by another column. In basic example the source table contains only two columns:
routeID nodeID nodeName
1 1 a
1 2 b
2 1 a
2 2 b
3 1 a
3 2 b
4 1 a
4 2 c
5 1 a
5 2 c
6 1 a
6 2 b
6 3 d
7 1 a
7 2 b
7 3 d
So, the routeID column refers to set of nodes which define a route.
What I need to do is to somehow group the routes, so that there will be only one unique sequence of nodes for one routeID.
In my actual case I tried to use window function to add columns which help to identify nodes sequence, but I still have no idea how to get those unique sequences and group routes.
As a final effect I want to get only unique routes - for example routes 1,2 and 3 aggregated to one route.
Do you have any idea how to help me ?
EDIT:
The other table which I would like to join with the one from the example may look like that:
journeyID nodeID nodeName routeID
1 1 a 1
1 2 b 1
2 1 a 1
2 2 b 1
3 1 a 4
3 2 c 4
...........................
...........................
You can try this idea:
DECLARE #DataSource TABLE
(
[routeID] TINYINT
,[nodeID] TINYINT
,[nodeName] CHAR(1)
);
INSERT INTO #DataSource ([routeID], [nodeID], [nodeName])
VALUES ('1', '1', 'a')
,('1', '2', 'b')
,('2', '1', 'a')
,('2', '2', 'b')
,('3', '1', 'a')
,('3', '2', 'b')
,('4', '1', 'a')
,('4', '2', 'c')
,('5', '1', 'a')
,('5', '2', 'c')
,('6', '1', 'a')
,('6', '2', 'b')
,('6', '3', 'd')
,('7', '1', 'a')
,('7', '2', 'b')
,('7', '3', 'd');
SELECT DS.[routeID]
,nodes.[value]
,ROW_NUMBER() OVER (PARTITION BY nodes.[value] ORDER BY [routeID]) AS [rowID]
FROM
(
-- getting unique route ids
SELECT DISTINCT [routeID]
FROM #DataSource DS
) DS ([routeID])
CROSS APPLY
(
-- for each route id creating CSV list with its node ids
SELECT STUFF
(
(
SELECT ',' + [nodeName]
FROM #DataSource DSI
WHERE DSI.[routeID] = DS.[routeID]
ORDER BY [nodeID]
FOR XML PATH(''), TYPE
).value('.', 'VARCHAR(MAX)')
,1
,1
,''
)
) nodes ([value]);
The code will give you this output:
So, you simple need to filter by rowID = 1. Of course, you can change the code as you like in order to satisfy your bussness criteria (for example showing no the first route ID with same nodes, but the last).
Also, ROW_NUMBER function cannot be used directly in the WHERE clause, so you need to wrap the code before filtering:
WITH DataSource AS
(
SELECT DS.[routeID]
,nodes.[value]
,ROW_NUMBER() OVER (PARTITION BY nodes.[value] ORDER BY [routeID]) AS [rowID]
FROM
(
-- getting unique route ids
SELECT DISTINCT [routeID]
FROM #DataSource DS
) DS ([routeID])
CROSS APPLY
(
-- for each route id creating CSV list with its node ids
SELECT STUFF
(
(
SELECT ',' + [nodeName]
FROM #DataSource DSI
WHERE DSI.[routeID] = DS.[routeID]
ORDER BY [nodeID]
FOR XML PATH(''), TYPE
).value('.', 'VARCHAR(MAX)')
,1
,1
,''
)
) nodes ([value])
)
SELECT DS2.*
FROM DataSource DS1
INNER JOIN #DataSource DS2
ON DS1.[routeID] = DS2.[routeID]
WHERE DS1.[rowID] = 1;
ok, let's use some recursion to create a complete node list for each routeID
First of all let's populate source table and journeyes tale
-- your source
declare #r as table (routeID int, nodeID int, nodeName char(1))
-- your other table
declare #j as table (journeyID int, nodeID int, nodeName char(1), routeID int)
-- temp results table
declare #routes as table (routeID int primary key, nodeNames varchar(1000))
;with
s as (
select *
from (
values
(1, 1, 'a'),
(1, 2, 'b'),
(2, 1, 'a'),
(2, 2, 'b'),
(3, 1, 'a'),
(3, 2, 'b'),
(4, 1, 'a'),
(4, 2, 'c'),
(5, 1, 'a'),
(5, 2, 'c'),
(6, 1, 'a'),
(6, 2, 'b'),
(6, 3, 'd'),
(7, 1, 'a'),
(7, 2, 'b'),
(7, 3, 'd')
) s (routeID, nodeID, nodeName)
)
insert into #r
select *
from s
;with
s as (
select *
from (
values
(1, 1, 'a', 1),
(1, 2, 'b', 1),
(2, 1, 'a', 1),
(2, 2, 'b', 1),
(3, 1, 'a', 4),
(3, 2, 'c', 4)
) s (journeyID, routeID, nodeID, nodeName)
)
insert into #j
select *
from s
now let's exctract routes:
;with
d as (
select *, row_number() over (partition by r.routeID order by r.nodeID desc) n2
from #r r
),
r as (
select d.*, cast(nodeName as varchar(1000)) Names, cast(0 as bigint) i2
from d
where nodeId=1
union all
select d.*, cast(r.names + ',' + d.nodeName as varchar(1000)), r.n2
from d
join r on r.routeID = d.routeID and r.nodeId=d.nodeId-1
)
insert into #routes
select routeID, Names
from r
where n2=1
table #routes will be like this:
routeID nodeNames
1 'a,b'
2 'a,b'
3 'a,b'
4 'a,c'
5 'a,c'
6 'a,b,d'
7 'a,b,d'
an now the final output:
-- the unique routes
select MIN(r.routeID) routeID, nodeNames
from #routes r
group by nodeNames
-- the unique journyes
select MIN(journeyID) journeyID, r.nodeNames
from #j j
inner join #routes r on j.routeID = r.routeID
group by nodeNames
output:
routeID nodeNames
1 'a,b'
4 'a,c'
6 'a,b,d'
and
journeyID nodeNames
1 'a,b'
3 'a,c'
I have following table (master_group) structure :
code name under
1 National Sales Manager 1
2 regional sales manager 1
3 area sales manager 2
4 sales manager 3
How do I get the ultimate parent of a particular row like :
code name under ultimateparent
1 National Sales Manager 1 1
2 regional sales manager 1 1
3 area sales manager 2 1
4 sales manager 3 1
With recursive cte going from top to childs:
with cte as(
select *, code as ultimate from t where code = under
union all
select t.*, c.ultimate from t
join cte c on c.code = t.under
where t.code <> t.under
)
select * from cte
For data:
create table t (code int, name varchar(100), under int)
insert into t values
(1, 'National Sales Manager', 1),
(2, 'regional sales manager', 1),
(3, 'area sales manager', 2),
(4, 'sales manager', 3),
(5, 'a', 5),
(6, 'b', 5),
(7, 'c', 5),
(8, 'd', 7),
(9, 'e', 7),
(10, 'f', 9),
(11, 'g', 9)
it generates the output:
code name under ultimate
1 National Sales Manager 1 1
5 a 5 5
6 b 5 5
7 c 5 5
8 d 7 5
9 e 7 5
10 f 9 5
11 g 9 5
2 regional sales manager 1 1
3 area sales manager 2 1
4 sales manager 3 1
Fiddle http://sqlfiddle.com/#!6/17c12e/1
You can use a recursive CTE to walk the tree and then choose the highest level for each code:
with cte as (
select mg.code, mg.name as name, mg.under as under, mg.under as parent, 1 as lev
from master_group mg
union all
select mg.code, mg.name, mg.under, cte.under as parent, cte.lev + 1
from master_group mg join
cte
on mg.under = cte.code
where cte.under is not null and cte.under <> mg.code
)
select code, name, under, parent as ultimateparent
from (select cte.*, max(lev) over (partition by cte.code) as maxlev
from cte
) t
where lev = maxlev;
Here is a SQL Fiddle.
I would put NULL as under (in my example ParentId) when it's the top record. With this assumption here's a solution
;
WITH Result AS
(
SELECT Id, ParentId, Name, Id as [Top] FROM
sample
where ParentId IS NULL
UNION ALL
SELECT s.Id, s.ParentId, s.Name, [Top]
FROM sample s INNER JOIN Result R ON s.ParentId = R.Id
)
http://sqlfiddle.com/#!6/13b9d/14
I suggest you to use a recursive function like this:
CREATE FUNCTION dbo.parentID (#code int)
RETURNS int AS
BEGIN
DECLARE #ResultVar int
SELECT #ResultVar = (SELECT under FROM master_group WHERE code = #code)
IF #ResultVar <> #code
BEGIN
SELECT #ResultVar = dbo.parentID(#ResultVar)
END
RETURN #ResultVar
END
GO
An use it like this:
SELECT *,
dbo.parentId(code) AS ultimateparent
FROM master_group
I'm going to shamelessly steal the data setup from another answer and demonstrate how you'd do this with hierarchyid:
create table t (code int, name varchar(100), under int)
insert into t values
(1, 'National Sales Manager', null),
(2, 'regional sales manager', 1),
(3, 'area sales manager', 2),
(4, 'sales manager', 3),
(5, 'a', null),
(6, 'b', 5),
(7, 'c', 5),
(8, 'd', 7),
(9, 'e', 7),
(10, 'f', 9),
(11, 'g', 9);
with cte as (
select code, name, under as parentCode, code as ultimateParent, cast('/' + cast(code as varchar) + '/' as nvarchar(max)) as h
from t
where under is null
union all
select child.code, child.name, child.under as ParentCode, parent.ultimateParentCode, cast(parent.h + cast(child.code as varchar) + '/' as nvarchar(max))
from t as child
join cte as parent
on child.under = parent.code
), hier as (
select code, name, parentCode, ultimateParentCode, cast(h as hierarchyid) as h
from cte
)
select code, name, parentCode, ultimateParentCode, h.ToString(), h.GetAncestor(h.GetLevel()-1).ToString()
from hier
Keep in mind, the recursive CTE need only be done once (or on data changes). The point that I'm making is that once you have a hierarchyid calculated (which you can store in row, btw), it's easy to answer the question you're posing with method calls on the hierarchyid (and possibly a join if you want to get back the progenitor's info).
I have a situation where I need to configure existing client data to address a problem where our application was not correctly updating IDs in a table when it should have been.
Here's the scenario. We have a parent table, where rows can be inserted that effectively replace existing rows; the replacement can be recursive. We also have a child table, which has a field that points to the parent table. In existing data, the child table could be pointing at rows that have been replaced, and I need to correct that. I can't simply update each row to the replacing row, however, because that row could have been replaced as well, and I need the latest row to be reflected.
I was trying to find a way to write a CTE that would accomplish this for me, but I'm struggling to find a query that finds what I'm actually looking for. Here's a sample of the tables that I'm working with; the 'ShouldBe' column is what I'd like my update query to end up with, taking into account the recursive replacement of some of the rows.
DECLARE #parent TABLE (SampleID int,
SampleIDReplace int,
GroupID char(1))
INSERT INTO #parent (SampleID, SampleIDReplace, GroupID)
VALUES (1, -1, 'A'), (2, 1, 'A'), (3, -1, 'A'),
(4, -1, 'A'), (5, 4, 'A'), (6, 5, 'A'),
(7, -1, 'B'), (8, 7, 'B'), (9, 8, 'B')
DECLARE #child TABLE (ChildID int, ParentID int)
INSERT INTO #child (ChildID, ParentID)
VALUES (1, 4), (2, 7), (3, 1), (4, 3)
Desired results in child table, after the update script has been applied:
ChildID ParentID ParentID_ShouldBe
1 4 6 (4 replaced by 5, 5 replaced by 6)
2 7 9 (7 replaced by 8, 8 replaced by 9)
3 1 2 (1 replaced by 2)
4 3 3 (unchanged, never replaced)
The following returns what you are looking for:
with cte as (
select sampleid, sampleidreplace, 1 as num
from #parent
where sampleidreplace <> -1
union all
select p.sampleid, cte.sampleidreplace, cte.num+1
from #parent p join
cte
on p.sampleidreplace = cte.sampleId
)
select c.*, coalesce(p.sampleid, c.parentid)
from #child c left outer join
(select ROW_NUMBER() over (partition by sampleidreplace order by num desc) as seqnum, *
from cte
) p
on c.ParentID = p.SampleIDReplace and p.seqnum = 1
The recursive part keeps track of every correspondence (4-->5, 4-->6). The addition number is a "generation" count. We actually want the last generation. This is identified by using the row_number() function, ordering by the num in decreasing order -- hence the p.seqnum = 1.
Ok, so it took me a while and there are probably better ways to do it, but here is one option.
DECLARE #parent TABLE (SampleID int,
SampleIDReplace int,
GroupID char(1))
INSERT INTO #parent (SampleID, SampleIDReplace, GroupID)
VALUES (1, -1, 'A'), (2, 1, 'A'), (3, -1, 'A'),
(4, -1, 'A'), (5, 4, 'A'), (6, 5, 'A'),
(7, -1, 'B'), (8, 7, 'B'), (9, 8, 'B')
DECLARE #child TABLE (ChildID int, ParentID int)
INSERT INTO #child (ChildID, ParentID)
VALUES (1, 4), (2, 7), (3, 1), (4, 3)
;WITH RecursiveParent1 AS
(
SELECT SampleIDReplace, SampleID, 1 RecursionLevel
FROM #parent
WHERE SampleIDReplace != -1
UNION ALL
SELECT A.SampleIDReplace, B.SampleID, RecursionLevel + 1
FROM RecursiveParent1 A
INNER JOIN #parent B
ON A.SampleId = B.SampleIDReplace
),RecursiveParent2 AS
(
SELECT *,
ROW_NUMBER() OVER(PARTITION BY SampleIdReplace ORDER BY RecursionLevel DESC) RN
FROM RecursiveParent1
)
SELECT A.ChildID, ISNULL(B.ParentID,A.ParentID) ParentID
FROM #child A
LEFT JOIN ( SELECT SampleIDReplace, SampleID ParentID
FROM RecursiveParent2
WHERE RN = 1) B
ON A.ParentID = B.SampleIDReplace
OPTION(MAXRECURSION 500)
I've got a iterative SQL loop that I think sorts this out as follows:
WHILE EXISTS (SELECT * FROM #child C INNER JOIN #parent P ON C.ParentID = P.SampleIDReplace WHERE P.SampleIDReplace > -1)
BEGIN
UPDATE #child
SET ParentID = SampleID
FROM #parent
WHERE #child.ParentID = SampleIDReplace
END
Basically, the while condition compares the contents of the parent ID column in the child table and sees if there is a matching value in the SampleIDReplace column of the parent table. If there is, it goes and gets the SampleID of that record. It only stops when the join results in every SampleIDReplace being -1, meaning we have nothing else to do.
On your sample data, the above results in the expected output.
Note that I had to use temp tables rather than table variables here in order for the table to be accessible within the loop. If you have to use table variables then there would need to be a bit more surgery done.
Clearly if you have deep replacement hierarchies then you'll do quite a few updates, which may be a consideration when looking to perform the query against a production database.