I have the following table:
NAME | SCORE
ALICE | 100
BOB | 90
CHARLES| 90
DUKE | 80
EVE | 70
...
My question is the following:
How can I extract with one query the name of the three best players? In my example the query should return four rows (ALICE, BOB, CHARLES and DUKE) because there are two silver medalists (they both have 90 points).
Thank You in advance.
Oracle has the DENSE_RANK analytical function for that exact purpose:
select name, score from (
select name, score, dense_rank() over(order by score desc nulls last) rank
-- ^^^^^^^^^^
-- reject NULL score at the end
from t
) V
where rank < 4
order by rank, name
See http://sqlfiddle.com/#!4/88445/5
How about the following
select *
from table1
where score >=
(select score from (
select score, rownum r from (
select distinct score from table1 order by score desc
) where rownum <= 3
) where r = 3)
order by score desc
See also this SQLFiddle: http://sqlfiddle.com/#!4/23e68/1
Related
I have a request to get some online courses.
This is an example of results I can get :
course_code | course_date | participant_name
------------+-------------+------------------
21175A | 2021-12-01 | Jon Doe
21175A | 2021-12-01 | Lisa Tia
21175A | 2021-13-01 | Jon Doe
21175A | 2021-13-01 | Lisa Tia
As you can see, I get multiple rows for the same course depending on the dates and the participants, so I have to do some process in PHP to put everything in an array with keys (course_code)
I want to make a pagination to get the 25 first courses (and not rows)
SELECT course_code, course_date, participant_name
FROM courses
ORDER BY course_date
OFFSET 0
FETCH NEXT 25 ROWS ONLY
This won't work because a course can take multiple rows (4 here). So I wonder if I can write a query to get the 25 first courses (based on the column course_code) even if there are 100 rows.
Do you have an idea ? Thank you in advance
EDIT : This is what I did :
WITH cte AS
(
SELECT course_code
FROM courses
WHERE course_date <= '2021-12-31'
ORDER BY course_code
OFFSET 0 ROWS
FETCH NEXT 25 ROWS ONLY
)
SELECT *
FROM courses
INNER JOIN cte ON cte.course_code = courses.course_code
WHERE course_date <= '2021-12-31'
I added the WHERE clause in both to make the request slower
Use DENSE_RANK:
WITH cte AS (
SELECT *, DENSE_RANK() OVER (ORDER BY course_code) dr
FROM courses
)
SELECT course_code, course_date, participant_name
FROM cte
WHERE dr <= 25
ORDER BY course_date;
For the pagination part, just change the inequality in the WHERE clause. For example, to get the second page of 25 courses per page, you would use WHERE dr > 25 AND dr <= 50.
So I have a table like this:
Taxi Client Time
Tom A 1
Tom A 2
Tom B 3
Tom A 4
Tom A 5
Tom A 6
Tom B 7
Tom B 8
Bob A 1
Bob A 2
Bob A 3
and the expected result will be like this:
Tom 3
Bob 1
I have used the partition function to count the consecutive value but the result become this:
Tom A 2
Tom A 3
Tom B 2
Bob A 2
Please help, I am not good in English, thanks!
This is a variation of a gaps-and-islands problem. You can solve it using window functions:
select taxi, count(*)
from (select t.taxi, t.client, count(*) as num_times
from (select t.*,
row_number() over (partition by taxi order by time) as seqnum,
row_number() over (partition by taxi, client order by time) as seqnum_c
from t
) t
group by t.taxi, t.client, (seqnum - seqnum_c)
having count(*) >= 2
)
group by taxi;
use distinct count
select taxi ,count( distinct cient)
from table_name
group by taxi
It seems your expected output is wrong
I don't see where you get the number 3 from. If you're trying to do what your question says and group by client in consecutive order only and then get the number of different groups, I can help you out with the following query. Bob has 1 group and Tom has 4.
Partition by taxi, ORDER BY taxi, time and check if this client matches the previous client for this taxi. If yes, do not count this row. If no, count this row, this is a new group.
SELECT FEE.taxi,
SUM(FEE.clientNotSameAsPreviousInSequence)
FROM
(
SELECT taxi,
CASE
WHEN PreviousClient IS NULL THEN
1
WHEN PreviousClient <> client THEN
1
ELSE
0
END AS clientNotSameAsPreviousInSequence
FROM
(
SELECT *,
LAG(client) OVER (PARTITION BY taxi ORDER BY taxi, time) AS PreviousClient
FROM table
) taxisWithPreviousClient
) FEE
GROUP BY FEE.taxi;
I have a large SQL table called 'allscores' similar to the following:
user score quiz_id high_score
Bob 90 math 1
John 80 math 0
John 85 math 1
Steve 100 math 1
Bob 95 reading 0
Bob 100 reading 1
John 80 reading 1
The 'high_score' field is in the table to begin with and is always set to '1' for the row where a user's score is the highest for them for that quiz.
What I want is a SQL query that I can run on an individual user to pull their highest score from each of the two quizzes ('math' and 'reading') along with their overall rank among scores for that quiz. What I have so far is the following:
SELECT `user`, `score`, `quiz_id` FROM `allscores` WHERE `user`="Bob" AND `high_score`="1"
Which will output the following:
user score quiz_id
Bob 90 math
Bob 100 reading
This query is simply pulling the highest score for Bob from each quiz - what I want to add is the ranking of the score among the scores in that particular quiz - so an output like the following:
user score quiz_id rank
Bob 90 math 2
Bob 100 reading 1
Bob's rank is '2' for the math quiz as Steve has a higher score, but he is ranked '1' for reading as he has the highest score.
How would I add this ranking column to my existing query?
This uses MS T-SQL syntax, but if your flavor of SQL uses window functions, it should be similar.
SQL Fiddle
MS SQL Server 2017 Schema Setup:
CREATE TABLE t (
[user] varchar(10)
, score int
, quiz_id varchar(10)
, high_score bit
) ;
INSERT INTO t ([user], score, quiz_id, high_score)
VALUES
( 'Bob',90,'math',1 )
, ( 'John',80,'math',0 )
, ( 'Steve',100,'math',1 )
, ( 'Bob',95,'reading',0 )
, ( 'Bob',100,'reading',1 )
, ( 'John',85,'math',1 )
, ( 'John',80,'reading',1 )
;
MAIN QUERY:
SELECT s1.[user]
, s1.score
, s1.quiz_id
, s1.high_score
--, s1.isUserHighScore
, s1.ranking
FROM (
SELECT
t.[user]
, t.score
, t.quiz_id
, t.high_score
--, ROW_NUMBER() OVER (PARTITION BY t.[user],t.quiz_id ORDER BY t.score DESC) AS isUserHighScore
, DENSE_RANK() OVER (PARTITION BY t.quiz_id ORDER BY t.score DESC ) AS ranking
FROM t
) s1
WHERE s1.[user]='Bob'
--AND s1.isUserHighScore = 1
AND s1.high_score = 1
Results:
| user | score | quiz_id | high_score | isUserHighScore | ranking |
|------|-------|---------|------------|-----------------|---------|
| Bob | 90 | math | true | 1 | 2 |
| Bob | 100 | reading | true | 1 | 1 |
I use ROW_NUMBER() to determine the highest score in a quiz for a user, then use DENSE_RANK() to figure out the rank of a users score versus others. The difference between DENSE_RANK() and RANK() is essentially that DENSE_RANK() won't leave any gaps in the ranking. Example: 2 people scored a 90 and 1 scored an 80, then with DENSE_RANK() the 90s would both be Rank 1 and the 80 would be Rank 2. With RANK(), the 90s would be Rank 1 and the 80 would be Rank 3.
I am trying to develop a query to pull out the top 2 months of sales by customer id. Here is a sample table:
Customer_ID Sales Amount Period
144567 40 2
234567 50 5
234567 40 7
144567 80 10
144567 48 2
234567 23 7
desired output would be
Customer_ID Sales Sum Period
144567 80 10
144567 48 2
234567 50 5
234567 40 7
I've tried
select sum(net_sales_usd_spot), valid_period, customer_id
from sales_trans_price_output
where valid_period in (select valid_period, sum(net_sales_usd_spot)
from sales_trans_price_output
where rank<=2)
group by valid_period, customer_id
error is
too many values ORA-00913.
I see why, but not sure how to rework it.
Try:
SELECT *
FROM (
SELECT t.*,
row_number() over (partition by customer_id order by sales_amount desc ) rn
FROM sales_trans_price t
)
WHERE rn <= 2
ORDER BY 1,2 desc
Demo: http://sqlfiddle.com/#!4/882888/3
what if you change your where clause to:
where valid_period in
(
select p.valid_period from sales_trans_price_output p
join (select valid_period, sum(net_sales_usd_spot)
from sales_trans_price_output
where rank<=2) s on s.valid_period = p.valid_period
)
It might be ugly and need refactoring, but I think this is the logic you're after.
The error is because of this.
where valid_period in (select valid_period, sum(net_sales_usd_spot)
from sales_trans_price_output
where rank<=2)
The subquery can only contain one field.
You are on the right track using rank, but you might not be using it correctly. Google oracle rank to find the correct syntax.
Back to what you are looking to achieve, a derived table is the approach I would use. That's simply a subquery with an alias. Or, if you use the keyword with, it might be called a CTE - Computed Table Expression.
Try it
SELECT * FROM (
SELECT T.*,
RANK () OVER (PARTITION BY CUSTOMER_ID
ORDER BY VALID_PERIOD DESC) FN_RANK
FROM SALES_TRANS_PRICE_OUTPUT T
) A
WHERE A.FN_RANK <= 2
ORDER BY CUSTOMER_ID ASC, VALID_PERIOD DESC, FN_RANK DESC
I'm trying to select N first rows from a database using ROWNUM. The problem is that if I want to select 6 first values of age with names of people with this age and some of the have the same value of age not every person will be shown.
For example
name age
Peter 15
Mark 22
Kelly 17
Mike 17
George 17
If I want to show people with 2 biggest values of age ROWNUM will show Mark and Kelly or Mike or George. Not all three of them. The expected result is:
Name age
Mark 22
Kelly 17
Mike 17
George 17
Is it possible to get this result using ROWNUM? Not RANK, DENSE_RANK, JOIN, correlated subquery but ROWNUM?
You can try something like this:
select *
from test
where age in (
select age
from (
select age
from test
group by age
order by age desc
)
where rownum <=2
)
The right solution dense_rank(), but you can do it with just row_number() and some subqueries:
select t.*
from t
where t.age in (select age
from (select age
from t t2
order by age desc
) x
where rownum <= 2
);
In Oracle 12+, you can simplify this:
select t.*
from t
where t.age in (select age
from t t2
order by age desc
fetch first 2 rows only
);