Query to rank rows in groups

问题

I'm using Apache Derby 10.10.

I have a list of participants and would like to calculate their rank in their country, like this:

|        Country |         Participant | Points | country_rank |
|----------------|---------------------|--------|--------------|
|      Australia |      Bridget Ciriac |      1 |            1 |
|      Australia |     Austin Bjorklun |      4 |            2 |
|      Australia |        Carrol Motto |      7 |            3 |
|      Australia |     Valeria Seligma |      8 |            4 |
|      Australia |     Desmond Miyamot |     27 |            5 |
|      Australia |      Maryjane Digma |     33 |            6 |
|      Australia |       Kena Elmendor |     38 |            7 |
|      Australia |         Emmie Hicke |     39 |            8 |
|      Australia |        Kaitlyn Mund |     50 |            9 |
|      Australia |    Alisia Vitaglian |     65 |           10 |
|      Australia |          Anika Bulo |     65 |           11 |
|             UK |          Angle Ifil |      2 |            1 |
|             UK |     Demetrius Buelo |     12 |            2 |
|             UK |      Ermelinda Mell |     12 |            3 |
|             UK |         Adeline Pee |     21 |            4 |
|             UK |     Alvera Cangelos |     23 |            5 |
|             UK |   Keshia Mccalliste |     23 |            6 |
|             UK |        Alayna Rashi |     24 |            7 |
|             UK |    Malinda Mcfarlan |     25 |            8 |
|  United States |     Gricelda Quirog |      3 |            1 |
|  United States |      Carmina Britto |      5 |            2 |
|  United States |         Noemi Blase |      6 |            3 |
|  United States |        Britta Swayn |      8 |            4 |
|  United States |        An Heidelber |     12 |            5 |
|  United States |        Maris Padill |     21 |            6 |
|  United States |     Rachele Italian |     21 |            7 |
|  United States |   Jacquiline Speake |     28 |            8 |
|  United States |      Hipolito Elami |     45 |            9 |
|  United States |          Earl Sayle |     65 |           10 |
|  United States |       Georgeann Ves |     66 |           11 |
|  United States |       Conchit Salli |     77 |           12 |

The schema looks like this (sqlfiddle):

create table Country(
  id INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY,
  name varchar(255),
  PRIMARY KEY (id)
);

create table Team(
  id INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY,
  country_id int not null,
  PRIMARY KEY (id),
  FOREIGN KEY (country_id) REFERENCES Country(id)
);

create table Participant(
  id INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY,
  team_id int not null,
  name varchar(100),
  points int,
  PRIMARY KEY (id),
  FOREIGN KEY (team_id) REFERENCES Team(id)
);

This is what I have tried:

select
    Country.name,
    Participant.name,
    Participant.points,
    ROW_NUMBER() OVER(order by Country.name, Participant.points) as country_rank
from Country
join Team
    on Country.id = Team.country_id
join Participant
    on Team.id = Participant.team_id;

But according to the apache derby doco, the OVER() statement doesn't take any arguments.

Does anyone have a way to achieve the country rank?

回答1:

Query

SELECT c.name AS Country,
       p.name AS Participant,
       p.points AS Points,
       (SELECT COUNT(*)
        FROM Participant p2
        JOIN Team t2 ON p2.team_id = t2.id
        WHERE t2.country_id = t.country_id
          AND (p2.points < p.points
               OR p2.points = p.points AND p2.name <= p.name)) AS country_rank
FROM Country c
JOIN Team t ON c.id = t.country_id
JOIN Participant p ON t.id = p.team_id
ORDER BY c.name, p.points, p.name;

Explanation

A simple ANSI-SQL subselect can be used to do the same job, counting the number of records for participants in the same country with a lower score or with the same score and a name that is alphabetically no higher.

Demo

SQL fiddle demo

回答2:

Consider a non-windows function SQL query that uses a correlated aggregate count subquery. Because the group column (Country.name) is not in same table as the rank criteria (Participant.points), we need to run same joins in the subquery but rename table aliases to properly compare inner and outer queries.

Now of course, in a perfect world that would be it but we must now account for tied points. Therefore, another very similar subquery (for tie breaker) is used to be added to first subquery. This second nested query matches inner and outer query's Country.name and Participant.points but ranks by alphabetical order of Participant.name.

SELECT
    Country.name AS Country,
    Participant.name AS Participant,
    Participant.points,
    (SELECT Count(*) + 1
       FROM Country subC
      INNER JOIN Team subT
              ON subC.id = subT.country_id
      INNER JOIN Participant subP
              ON subT.id = subP.team_id
      WHERE subC.name = Country.name
        AND subP.points < Participant.points) 

     +

    (SELECT Count(*)
       FROM Country subC
      INNER JOIN Team subT
              ON subC.id = subT.country_id
      INNER JOIN Participant subP
              ON subT.id = subP.team_id
      WHERE subC.name = Country.name
        AND subP.points = Participant.points
        AND subP.name < Participant.name)  As country_rank

FROM Country
INNER JOIN Team
        ON Country.id = Team.country_id
INNER JOIN Participant
        ON Team.id = Participant.team_id
ORDER BY Country.name, Participant.points;

回答3:

all you need to add is a partition by country and that should give you what you need.

SELECT
Country.name,
Participant.name,
Participant.points,
ROW_NUMBER() OVER(PARTITION BY country order by Country.name, Participant.points) as country_rank
from Country
join Team
  on Country.id = Team.country_id
join Participant
  on Team.id = Participant.team_id;

来源：https://stackoverflow.com/questions/35778746/query-to-rank-rows-in-groups

标签

sql

derby

rank

row-number

groupwise-maximum