I need to delete some rows in the dataset, of which the speed equals zero and lasting over N times (let's assume N is 2).
The structure of the table demo looks like:
id
car
speed
time
1
foo
0
1
2
foo
0
2
3
foo
0
3
4
foo
1
4
5
foo
1
5
6
foo
0
6
7
bar
0
1
8
bar
0
2
9
bar
5
3
10
bar
5
4
11
bar
5
5
12
bar
5
6
Then I hope to generate a table like the one below by using window_function:
id
car
speed
time
lasting
1
foo
0
1
3
2
foo
0
2
3
3
foo
0
3
3
4
foo
1
4
2
5
foo
1
5
2
6
foo
0
6
1
7
bar
0
1
2
8
bar
0
2
2
9
bar
5
3
4
10
bar
5
4
4
11
bar
5
5
4
12
bar
5
6
4
Then I can easily exclude those rows by using WHERE NOT (speed = 0 AND lasting > 2)
Put the code I tried here, but it didn't return the value I expected and I guess those FROM (SELECT ... FROM (SELECT ... might not be the best practice to solve the problem:
SELECT g3.*, count(id) OVER (PARTITION BY car, cumsum ORDER BY id) as num
FROM (SELECT g2.*, sum(grp2) OVER (PARTITION BY car ORDER BY id) AS cumsum
FROM (SELECT g1.*, (CASE ne0 WHEN 0 THEN 0 ELSE 1 END) AS grp2
FROM (SELECT g.*, speed - lag(speed, 1, 0) OVER (PARTITION BY car) AS ne0
FROM (SELECT *, row_number() OVER (PARTITION BY car) AS grp FROM demo) g ) g1 ) g2 ) g3
ORDER BY id;
You can use window function LAG() to check for the previous speed value for each row and SUM() window function to create the groups for the continuous values.
Then with COUNT() window function you can count the number of rows in each group so that you can filter out the rows with 0 speed in the groups that have more than 2 rows:
SELECT id, car, speed, time
FROM (
SELECT *, COUNT(*) OVER (PARTITION BY car, grp) counter
FROM (
SELECT *, SUM(flag::int) OVER (PARTITION BY car ORDER BY time) grp
FROM (
SELECT *, speed <> LAG(speed, 1, speed - 1) OVER (PARTITION BY car ORDER BY time) flag
FROM demo
) t
) t
) t
WHERE speed <> 0 OR counter <= 2
ORDER BY id;
See the demo.
Id values
1 10
1 20
1 30
1 40
2 3
2 9
2 0
3 14
3 5
3 7
Answer should be
Id values
1 30
2 3
3 7
I tried as below
Select distinct
id,
(select max(values)
from table
where values not in(select ma(values) from table)
)
You need the row_number window function. This adds a column with a row count for each group (in your case the ids). In a subquery you are able to ask for the second row of each group.
demo:db<>fiddle
SELECT
id, values
FROM (
SELECT
*,
row_number() OVER (PARTITION BY id ORDER BY values DESC)
FROM
table
) s
WHERE row_number = 2
I am having trouble figuring out how I can use recursive CTEs to order my results recursively. Here is what I mean (this is a simplified dataset):
I have this as input:
declare #sections table (id int, parent int);
insert into #sections values (1, 1);
insert into #sections values (2, 2);
insert into #sections values (3, 2);
insert into #sections values (4, 2);
insert into #sections values (5, 4);
insert into #sections values (6, 1);
insert into #sections values (7, 6);
insert into #sections values (8, 6);
insert into #sections values (9, 6);
insert into #sections values (10, 9);
-- hierarchical view
--1
-- 6
-- 7
-- 8
-- 10
-- 9
--2
-- 3
-- 4
-- 5
And I want this as output
EDIT: The order of the rows is the important part here
-- id parent depth
-- 1 1 0
-- 6 1 1
-- 7 6 2
-- 8 6 2
-- 10 8 3
-- 9 6 2
-- 2 2 0
This is the best I can do:
with section_cte as
(
select id, parent, 0 'depth' from #sections where id = parent
union all
select cte.id, cte.parent, depth + 1
from #sections s join section_cte cte on s.parent = cte.id where s.id <> s.parent
)
select *from section_cte
Can anyone please help me tweak this query to get what I need?
Thanks!
You missed the part where you need to identify the depth is from the cte
WITH CTE AS (
SELECT
id
, parent
, 0 AS depth
FROM
#sections
WHERE
id=parent
UNION ALL
SELECT
s.id
, s.parent
, c.depth + 1
FROM
#sections s
JOIN CTE c ON s.parent=c.id AND s.id <> s.parent
)
SELECT *
FROM CTE;
During the recursive build, it is a small matter to add a sequence. In the example below, the order is driven by the alphabetical order of the title, but you can use any other available key/sequence.
Declare #Table table (ID int,Pt int,Title varchar(50))
Insert into #Table values (0,null,'Tags'),(1,0,'Transportation'),(2,1,'Boats'),(3,1,'Cars'),(4,1,'Planes'),(5,1,'Trains'),(6,0,'Technology'),(7,6,'FTP'),(8,6,'HTTP'),(9,0,'Finance'),(10,9,'FTP'),(11,9,'401K'),(12,2,'Sail'),(13,2,'Powered'),(14,6,'Internet'),(15,6,'Database'),(16,15,'SQL Server'),(17,15,'MySQL'),(18,15,'MS Access')
Declare #Top int = null --<< Sets top of Hier Try 9
Declare #Nest varchar(25) =' ' --<< Optional: Added for readability
;with cteHB (Seq,ID,Pt,Lvl,Title) as (
Select Seq = cast(1000+Row_Number() over (Order by Title) as varchar(500))
,ID
,Pt
,Lvl=1
,Title
From #Table
Where IsNull(#Top,-1) = case when #Top is null then isnull(Pt,-1) else ID end
Union All
Select Seq = cast(concat(cteHB.Seq,'.',1000+Row_Number() over (Order by cteCD.Title)) as varchar(500))
,cteCD.ID
,cteCD.Pt,cteHB.Lvl+1
,cteCD.Title
From #Table cteCD
Join cteHB on cteCD.Pt = cteHB.ID)
,cteR1 as (Select Seq,ID,R1=Row_Number() over (Order By Seq) From cteHB)
,cteR2 as (Select A.Seq,A.ID,R2=Max(B.R1) From cteR1 A Join cteR1 B on (B.Seq like A.Seq+'%') Group By A.Seq,A.ID )
Select Hier='HierName'
,B.R1
,C.R2
,A.ID
,A.Pt
,A.Lvl
,Title = Replicate(#Nest,A.Lvl) + A.Title
--,A.Seq --<< Normally Excluded, but you can see how the sequence is built
From cteHB A
Join cteR1 B on A.ID=B.ID
Join cteR2 C on A.ID=C.ID
Order By A.Seq --<< Use R1 if Range Keys are used
Returns
Hier R1 R2 ID Pt Lvl Title
HierName 1 19 0 NULL 1 Tags
HierName 2 4 9 0 2 Finance
HierName 3 3 11 9 3 401K
HierName 4 4 10 9 3 FTP
HierName 5 12 6 0 2 Technology
HierName 6 9 15 6 3 Database
HierName 7 7 18 15 4 MS Access
HierName 8 8 17 15 4 MySQL
HierName 9 9 16 15 4 SQL Server
HierName 10 10 7 6 3 FTP
HierName 11 11 8 6 3 HTTP
HierName 12 12 14 6 3 Internet
HierName 13 19 1 0 2 Transportation
HierName 14 16 2 1 3 Boats
HierName 15 15 13 2 4 Powered
HierName 16 16 12 2 4 Sail
HierName 17 17 3 1 3 Cars
HierName 18 18 4 1 3 Planes
HierName 19 19 5 1 3 Trains
Now, you may have noticed R1 and R2. These are my range keys, and are often used to aggregate data without recursion. If you don't need or want these, just remove the cteR1 and cteR2 (and the corresponding references in the final SELECT).
EDIT
You also have the option of selecting a portion of the hierarchy (i.e. Technology and its children).
The trick you need is to create a sortstring which match your business rule. Something like this.
WITH CTE AS (
SELECT
id, parent, 0 AS depth
--For MS SQL Server 2012+
,cast(format(id,'0000') as varchar(max)) sort
--For previous versions
,cast(stuff('0000',5-len(cast(id as varchar)),len(cast(id as varchar)),id) as varchar(max)) sort1
FROM #sections
WHERE id=parent
UNION ALL
SELECT s.id, s.parent, c.depth + 1
,sort + cast(format(s.id,'0000') as varchar(max)) sort
,sort + cast(stuff('0000',5-len(cast(s.id as varchar)),len(cast(s.id as varchar)),s.id) as varchar(max)) sort1
FROM #sections s
inner join CTE c ON s.parent=c.id AND s.id <> s.parent
)
SELECT *
FROM CTE
order by sort --or by sort1 depending on version
Let's say I have an array of integers
1 6 6 3 3 8 4 4
It will be always of the form n*(pairs of number) + 2 (unique numbers).
Is there an efficient way of keeping only the 2 uniques values (i.e. the 2 with single occurence)?
Here, I would like to get 1 and 8.
So far is what I have:
SELECT node_id
FROM
( SELECT node_id, COUNT(*)
FROM unnest(array[1, 6, 6 , 3, 3 , 8 , 4 ,4]) AS node_id
GROUP BY node_id
) foo
ORDER BY count LIMIT 2;
You are very close, I think:
SELECT node_id
FROM (SELECT node_id, COUNT(*)
FROM unnest(array[1, 6, 6 , 3, 3 , 8 , 4 ,4]) AS node_id
GROUP BY node_id
HAVING count(*) = 1
) foo ;
You can group these back into an array, if you like, using array_agg().
My table has a parent/child relationship, along the lines of parent.id,id. There is also a column that contains a quantity, and another ID representing a grand-parent, like so:
id parent.id qty Org
1 1 1 100
2 1 0 100
3 1 4 100
4 4 1 101
5 4 2 101
6 6 1 102
7 6 0 102
8 6 1 102
What this is supposed to show is ID 1 is the parent, and ID 2 and 3 are children which belongs to ID 1, and ID 1, 2, and 3 all belong to the grandparent 100.
I would like to know if any child or parent has QTY = 0, what are all the other id's associated to that parent, and what are all the other parents associated with that grandparent?
For example, I would want to see a report that shows me this:
Org id parent.id qty
100 1 1 1
100 2 1 0
100 3 1 4
102 6 6 1
102 7 6 0
102 8 6 1
Much appreciate any help you can offer to build a MS SQL 2000 (yeah, I know) query to handle this.
Try this
select * from tablename a
where exists (select 1 from tablename x
where x.parent_id = a.parent_id and qty = 0)
Example:
;with cte as
( select 1 id,1 parent_id, 1 qty, 100 org
union all select 2,1,0,100
union all select 3,1,4,100
union all select 4,4,1,101
union all select 5,4,2,101
union all select 6,6,1,102
union all select 7,6,0,102
union all select 8,6,1,102
)
select * from cte a
where exists (select 1 from cte x
where x.parent_id = a.parent_id and qty = 0)
SQL DEMO HERE