Hi I have a table that looks like this
StudentID
ParentID
Rank
1
11
1
1
15
5
1
16
6
2
21
1
2
22
2
3
31
1
3
37
7
3
38
8
4
41
1
4
42
2
So I want to pull only the top 2 ranks per student the out come will look like:
StudentID
ParentID
Rank
1
11
1
1
15
5
2
21
1
2
22
2
3
31
1
3
37
7
4
41
1
4
42
2
What would be the best way to do this? What makes it complicated is that every student has a parent ranked 1 but not every student has a parent ranked 2. What sql statement would I use to pull just the next ranked parent after 1?
The canonical solution is to use row_number():
select t.*
from (select t.*,
row_number() over (partition by studentid order by rank) as seqnum
from t
) t
where seqnum <= 2;
Under some circumstances, it might be faster to use:
select t.*
from t
where t.rank in (select top (2) t2.rank
from t t2
where t2.studentid = t.studentid
order by rank asc
) ;
I think this might have better performance if there were few students that had lots of ranks per student and you had an index on studentid, rank.
Related
My current T-SQL query provides the following results:
Query:
WITH CTE AS
(
SELECT SubscriberID, sum(valueMB) as ValuesMB
FROM dbo.InternetNetwork
GROUP BY SubscriberID
),
CTE2 AS (
SELECT ab.planID, a.SubscriberID, MAX(ValuesMB) as MaximumValue
FROM CTE AS a
left join
Subscriber as ab on a.SubscriberID= ab.SubscriberID
GROUP BY ab.planID, a.SubscriberID
)
select *
FROM CTE2 as b
ORDER BY b.MaximumValue desc
Output:
planID | SubscriberID | MaxValue
19 1555 97536.00
18 3528 97478.00
2 4029 93413.00
Query #2:
WITH CTE AS
(
SELECT SubscriberID, sum(valueMB) as ValuesMB
FROM dbo.InternetNetwork
GROUP BY SubscriberID
),
CTE2 AS(
SELECT ab.planID, MAX(ValuesMB) as MaximumValue
FROM CTE AS a
left join
Subscriber as ab on a.SubscriberID= ab.SubscriberID
GROUP BY ab.planID
)
SELECT pl.OperatorID, MAX(b.MaximumValue) as Super
FROM CTE2 as b
left join
Plan as pl on b.planID= pl.planID
GROUP BY pl.operatorID
ORDER BY pl.operatorID
Output #2:
OperatorID | Value
1 93413.00
2 86017.00
3 97536.00
I would like to also include a subscriberID, but I'm unable to figure out a way to do so, as the only way to do it, is including in the last SELECT and adding to GROUP BY, which when done, makes a mess of a result which is not accurate.
My desired output:
OperatorID | Value | SubscriberID
1 93413.00 4029
2 86017.00 164
3 97536.00 1544
internet network data:
SubscriberID ValuesMB
1 28
1 27
2 27
2 27
2 27
3 29
3 28
3 27
3 27
4 27
4 27
4 29
Subscriber Data:
SubscriberID PersonID PlanID
1 1 3
2 2 10
3 2 6
4 3 14
5 3 1
6 4 18
7 5 5
8 5 1
9 5 9
10 5 16
11 6 13
12 6 13
13 6 20
14 6 16
15 7 4
Plan data
PlanID OperatorID
1 1
2 1
3 2
4 2
5 2
6 2
7 2
8 2
9 2
10 2
11 2
12 3
13 3
14 3
15 3
16 3
17 3
18 3
19 3
20 3
The tables are somewhat like this related InternetNetwork-> Subscriber -> Plan. InternetNetwork contains how much each Subscribed has used. Each Subscriber has Plan associated with him. Each Plan contains a different Operator, there are only three. I wish to list all three operators, the data transferred by the subscriber of the plan that has the operator and Subscriber ID.
Window functions allow you to have fields in your select along with aggregate functions. You can do something like this
;WITH CTE AS
(
SELECT I.SubscriberID,
S.PlanID,
SUM(ValuesMB) OVER(PARTITION BY i.SubscriberID)as ValuesMB
FROM dbo.InternetNetwork I
JOIN Subscriber S
ON I.SubscriberID = S.SubscriberID
),
CTE2 AS
(
SELECT p.operatorID,
a.SubscriberID,
a.ValuesMB,
ROW_NUMBER() OVER(PARTITION BY p.operatorID ORDER BY a.ValuesMB DESC) as rn
FROM CTE a
join [Plan] P
on a.planID = P.planID
)
SELECT operatorID,
ValuesMB,
SubscriberID
FROM CTE2
where rn = 1
I have a table in an SQL Server database on the following form, sorted according to id.
id group
1 10
17 10
24 10
2 20
16 20
72 20
104 20
8 30
9 30
I would like to select every row grouped according to the row group and add the following information to this table: the order (as sorted) within the group and whether the row is the last row in the group. In other words, something similar to this:
id group order last
1 10 1 0
17 10 2 0
24 10 3 1
2 20 1 0
16 20 2 0
72 20 3 0
104 20 4 1
8 30 1 0
9 30 2 1
I've tried fiddling around with ROW_NUMBER, but I'm not all that experienced with SQL Server and I can't get it to work. Does anyone have a suggestion?
Use ROW_NUMBER window function
select id,[group],
row_number()over(partition by [group] order by id) as [order],
case when row_number()over(partition by [group] order by id desc) = 1 then 1 else 0 end as Last
From yourtable
I need to make a query over an SQL Server table but I don't know exactly how.
Consider this table (the real table is much more complex, Ord1 and Ord2 are dates that could be null, but i simplified it to this case):
Data of MyTable
ID MaqID Ord1 Ord2
------------------------
1 144 4 3
2 144 2 1
3 12 2 3
4 144 3 5
5 12 3 1
6 144 4 2
7 12 2 4
8 144 2 3
9 12 1 5
10 12 3 2
I need records for specific MaqID in Specific Order. I get that with this Query:
SELECT * FROM myTable WHERE MaqID=144 ORDER BY MaqID, Order1 DESC, Order2
Wich give me:
ID MaqID Ord1 Ord2
------------------------
6 144 4 2
1 144 4 3
4 144 3 5
2 144 2 1
8 144 2 3
Now, I need a single query that, for each MaqID, return the first ID for each subquery following above order. The result should be:
Expected result
MaqID ID
-----------
144 6
12 5
I have already try distinct conbination of TOP a MAX, but TOP result only one result and i need one for each MaqID, and for Max I have not field to maximize.
To sumarize: I need the first ID for each MaqID from a subquery in a specific order
Any ideas? Thanks!
You can do this using row_number():
select t.*
from (select t.*,
row_number() over (partition by macid Order1 DESC, Order2) as seqnum
from mytable t
) t
where seqnum = 1;
I have a table which rank the items which i have.
I need a queries which will pick up only the top 2 ranks for a given item, the rank may not be in sequential order.
I need to fetch the item with least two ranks, there will same rank for two items as well.
Here is the snap shot of my table.
Item Id Supp Id Rank
1 2 2
1 1 7
1 7 5
1 9 11
2 67 4
2 9 14
2 10 14
2 34 4
2 25 3
2 60 3
2 79 5
my requirement is if I enter 2 i should get the result as below
Item Id Supp_id Rank
2 25 3
2 60 3
2 67 4
2 34 4
I am using oracle 10g version.
As one of the approaches it can be done as follows. Here we are using dense_rank() over() analytic function to assign a rank for a row in a ordered by rank group of rows .
select t.item_id
, t.supp_id
, t.rank
from (select item_id
, supp_id
, rank
, dense_rank() over(partition by item_id
order by rank) as rn
from t1
where item_id = 2
) t
where t.rn <= 2
Result:
ITEM_ID SUPP_ID RANK
---------- ---------- ----------
2 25 3
2 60 3
2 67 4
2 34 4
SQLFiddle Demo
I have 2 tables: Persons(idPerson INT) and Questions(idQuestion INT).
I want to insert the data into a 3rd table: OrderedQuestions(idPerson INT, idQuestion INT, questionRank INT)
I want to assign all the questions to all the persons but in a random order.
I thought of doing a CROSS JOIN but then, I get the same order of questions for every persons.
INSERT INTO OrderedQuestions
SELECT idPerson, idQuestion, questionRank FROM Persons
CROSS JOIN
(SELECT idQuestion,ROW_NUMBER() OVER (ORDER BY NEWID()) as questionRank
FROM Questions) as t
How can I achieve such a random, distinct ordering for every persons?
Obviously, I want the solution to be as fast as possible.
(It can be done using TSQL or Linq to SQL)
Desired results for 3 persons and 5 questions:
idPerson idQuestion questionRank
1. 1 18 1
2. 1 14 2
3. 1 25 3
4. 1 31 4
5. 1 2 5
6. 2 2 1
7. 2 25 2
8. 2 31 3
9. 2 18 4
10. 2 14 5
11. 3 31 1
12. 3 18 2
13. 3 14 3
14. 3 25 4
15. 3 2 5
I just edited the results (Since the IDs are autogenerated, they can't be used to order the questions).
This could probably be written more efficently, but it meets all the reqs.
SELECT
idperson,
idQuestion,
ROW_NUMBER() OVER (PARTITION BY personid ORDER BY ordering) as questionRank
FROM (
SELECT idperson, idQuestion, ordering
FROM person
CROSS JOIN
(
SELECT idQuestion, NewID() as ordering FROM Question
) as t
) as a
order by personid, QuestionRank