I am working on writing a sql to get the SID and SNAME. In this task, I need to count which team win the max number of League and find out the SID.
Leagues(LID, CHAMPION_TID)
LID: League ID ; CHAMPION_TID: champion team ID
SUPPORT(SID, LID)
SPONSORS(SID, SNAME)
PRIMARY KEY: LID,SID
Now, I can find out which team win the max number of League through the following SQL:
SELECT
MAX(y.cham)
FROM
(SELECT
CHAMPION_TID, COUNT(L.CHAMPION_TID) AS cham
FROM
LEAGUES L
GROUP BY
L.CHAMPION_TID) y, LEAGUES L
WHERE
y.CHAMPION_TID = L.CHAMPION_TID;
I am confusing in the following step. My idea get the LID, then use the join table to display SID and SNAME. But I suck in this step.
SELECT L.LID, MAX(y.cham)
FROM
(SELECT CHAMPION_TID, COUNT(L.CHAMPION_TID) AS cham
FROM LEAGUES L
GROUP BY L.CHAMPION_TID) y, LEAGUES L
WHERE
y.CHAMPION_TID = L.CHAMPION_TID
You can use the following to find the Sponsor ID and Sponsor Name:
SELECT DISTINCT
sp.SID,
sp.SNAME
FROM
LEAGUES l3
INNER JOIN support s ON
l3.LID = s.LID
INNER JOIN SPONSORS sp ON
s.SID = sp.SID
WHERE
l3.CHAMPION_TID IN (
SELECT
l2.CHAMPION_TID
FROM
LEAGUES l2
GROUP BY
l2.CHAMPION_TID
HAVING
count(l2.CHAMPION_TID) = (
SELECT
count(l1.CHAMPION_TID)
FROM
LEAGUES l1
GROUP BY
l1.CHAMPION_TID
ORDER BY
count(l1.CHAMPION_TID) DESC
FETCH FIRST 1 ROW ONLY
)
);
It finds the count of CHAMPION_TID in LEAGUES, orders it by desc (such that the highest count is always on top), then uses it to find the associated CHAMPION_TID. It handles ties for max(count(CHAMPION_TID)) as well :)
If fetch first 1 row only does not work, you can use select top 1 l1.CHAMPION_TID...
Here is a working demo using Postgres.
Related
The question im trying to answer is : to find the names of guest who visited more than 2 different restaurants on 15-JUNE-20.
There is a:
Guest table with GID,Gname
Visit table with VID, GID, RESTID, VDATE
Restaurant table with RESTID, RNAME
whenever i tried introducing the groupby i would get the error
SELECT GuestN.GID, GuestN.Gname
FROM GuestN
WHERE GuestN.GID IN (
SELECT VisitN.GID
FROM VisitN
WHERE VisitN.Vdate = '15-JUN-20' AND VisitN.restID IN (
SELECT RestaurantN.Restid
FROM RestaurantN having count(*)>2));
The table RestaurantN is not needed since you have restID in the table VisitN and you are not interested in the restaurant'a name, but only on their number.
Join GuestN to VisitN, aggregate and set the condition in the HAVING clause:
SELECT g.GID, g.Gname
FROM GuestN g INNER JOIN VisitN v
ON v.GID = g.GID
WHERE v.Vdate = '15-JUN-20'
GROUP BY g.GID, g.Gname
HAVING COUNT(DISTINCT v.restID) > 2
I have to say who is the scientist who have been the most in mission. I tried this code but it wasn't successful:
select name
from scientist, mission
where mission.nums = chercheur.nums
having count(*) = (select max(count(numis)) from mission, scientist where
mission.nums = chercheur.nums
group by name)
I have done several modifications for this request but I only obtain errors (ora-0095 and ora-0096 if I remember correctly).
Also, I create my tables with:
CREATE TABLE Scientist
(NUMS NUMBER(8),
NAME VARCHAR2 (15),
CONSTRAINT CP_CHER PRIMARY KEY (NUMS));
CREATE TABLE MISSION
(NUMIS NUMBER(8),
Country VARCHAR2 (15),
NUMS NUMBER(8),
CONSTRAINT CP_MIS PRIMARY KEY (NUMIS),
CONSTRAINT CE_MIS FOREIGN KEY (NUMS) REFERENCES SCIENTIST (NUMC));
You could count the missions each scientist participated in, and wrap that query in a query with a window function that will rank them according to their participation:
SELECT name
FROM (SELECT name, RANK() OVER (PARTITION BY name ORDER BY cnt DESC) AS rk
FROM (SELECT name, COUNT(*) AS cnt
FROM scientist s
JOIN mission m ON s.nums = m.nums
GROUP BY name) t
) q
WHERE rk = 1
Step 0 : Format your code :-) It would make it much easier to visualize
Step 1 : Get the count of Numis by Nums in the Mission table. This will tell you how many missions were done by each Nums
This is done in the cte block cnt_by_nums
Next to get the name of the scientist by joining cnt_by_nums with scientist table.
After that you want to get only those scientists who have the cnt_by_missions as the max available value from cnt_by_num
with cnt_by_nums
as (select Nums,count(Numis) as cnt_missions
from mission
group by Nums
)
select a.Nums,max(b.Name) as name
from cnt_by_nums a
join scientist b
on a.Nums=b.Nums
group by a.Nums
having count(a.cnt_missions)=(select max(a1.cnt_missions) from cnt_by_nums a1)
I'd write a query like this:
SELECT NAME, COUNTER
FROM
(SELECT NAME, COUNT(*) AS COUNTER
FROM SCIENTIST S
LEFT JOIN MISSION M
ON S.NUMS=M.NUMS
GROUP BY NAME) NUM
INNER JOIN
(SELECT MAX(COUNTER) AS MAX_COUNTER FROM
(SELECT NAME, COUNT(*) AS COUNTER
FROM SCIENTIST S
LEFT JOIN MISSION M
ON S.NUMS=M.NUMS
GROUP BY NAME) C) MAX
ON NUM.COUNTER=MAX.MAX_COUNTER;
(it works on MYSQL, I hope it's the same in Oracle)
As you don't select the name of your scientist (only count their missions) you don't need to join those tables within the subquery. Grouping over the foreign key would be sufficient:
select count(numis) from mission group by nums
You column names are a bit weird but that's your choice ;-)
Selecting only the scientist with the most mission references could be achieved in two ways. One way would be your approach where you may get multiple scientists if they have the same max missions.
The first problem you have in your query is that you are checking an aggregation (HAVING COUNT(*) = ) without grouping. You are only grouping your subselect.
Second, you could not aggregate an aggregation (MAX(COUNT)) but you may select only the first row of that subselect ordered by it's size or select the max of it by subquerying the subquery.
Approach with only one line:
select s.name from scientist s, mission m
where m.nums = s.nums
group by name
having count(*) =
(select count(numis) from mission
group by nums
order by 1 desc
fetch first 1 row only)
Approach with double subquery:
select s.name from scientist s, mission m
where m.nums = s.nums
group by name having count(*) =
(select max(numis) from
(select count(numis) numis from mission group by nums)
)
Second approach would be doing the FETCH FIRST on yur final result but this would give you exactly 1 scientist even if there are multiple with the same max missions:
select s.name from scientist s, mission m
where m.nums = s.nums
group by name
order by count(*) desc
fetch first 1 row only
Doing a cartisian product is not state of the art but the optimizer would make it a "good join" with the given reference in the where clause.
Made these with IBM Db2 but should also work on Oracle.
If you want one row, then in Oracle 12+, you can do:
SELECT name, COUNT(*) AS cnt
FROM scientist s JOIN
mission m
ON s.nums = m.nums
GROUP BY name
ORDER BY COUNT(*) DESC
FETCH FIRST 1 ROW ONLY;
In earlier versions, you would generally use a subquery:
SELECT s.*
FROM (SELECT name, COUNT(*) AS cnt
FROM scientist s JOIN
mission m
ON s.nums = m.nums
GROUP BY name
ORDER BY COUNT(*) DESC
) sm
WHERE rownum = 1;
If you want ties, then generally window functions would be a simple solution:
SELECT s.*
FROM (SELECT name, COUNT(*) AS cnt,
RANK() OVER (ORDER BY COUNT(*) DESC) as seqnum
FROM scientist s JOIN
mission m
ON s.nums = m.nums
GROUP BY name
ORDER BY COUNT(*) DESC
) sm
WHERE seqnum = 1;
Lets say i've got a db with 3 tables:
Players (PK id_player, name...),
Tournaments (PK id_tournament, name...),
Game (PK id_turn, FK id_tournament, FK id_player and score)
Players participate in tournaments. Table called Game keeps track of each player's score for different tournaments)
I want to create a view that looks like this:
torunament_name Winner highest_score
Tournament_1 Jones 300
Tournament_2 White 250
I tried different aproaches but I'm fairly new to sql (and alsoto this forum)
I tried using union all clause like:
select * from (select "Id_player", avg("score") as "Score" from
"Game" where "Id_tournament" = '1' group by "Id_player" order by
"Score" desc) where rownum <= 1
union all
select * from (select "Id_player", avg("score") as "Score" from
"Game" where "Id_tournament" = '2' group by "Id_player" order by
"Score" desc) where rownum <= 1;
and ofc it works but whenever a tournament happens, i would have to manually add a select statement to this with Id_torunament = nextvalue
EDIT:
So lets say that player with id 1 scored 50 points in tournament a, player 2 scored 40 points, player 1 wins, so the table should show only player 1 as the winner (or if its possible 2or more players if its a tie) of this tournament. Next row shows the winner of second tournament. I dont think Im going to put multiple games for one player in the same tournament, but if i would, it would probably count avg from all his scores.
EDIT2:
Create table scripts:
create table players
(id_player numeric(5) constraint pk_id_player primary key, name
varchar2(50));
create table tournaments
(id_tournament numeric(5) constraint pk_id_tournament primary key,
name varchar2(50));
create table game
(id_game numeric(5) constraint pk_game primary key, id_player
numeric(5) constraint fk_id_player references players(id_player),
id_tournament numeric(5) constraint fk_id_tournament references
tournaments(id_tournament), score numeric(3));
RDBM screenshot
FINAL EDIT:
Ok, in case anyone is wondering I used Jorge Campos script, changed it a bit and it works. Thank you all for helping. Unfortunately I cannot upvote comments yet, so I can only thank by posting. Heres the final script:
select
t.name,
p.name as winner,
g.score
from
game g inner join tournaments t
on g.id_tournament = t.id_tournament
inner join players p
on g.id_player = p.id_player
inner join
(select g.id_tournament, g.id_player,
row_number() over (partition by t.name order by
score desc) as rd from game g join tournaments t on
g.id_tournament = t.id_tournament
) a
on g.id_player = a.id_player
and g.id_tournament = a.id_tournament
and a.rd=1
order by t.name, g.score desc;
This query could be simplified depending on the RDBMs you are using.
select
t.name,
p.name as winner,
g.score
from
game g inner join tournaments t
on g.id_tournament = t.id_tournament
inner join players p
on g.id_player = p.id_player
inner join
(select id_tournament,
id_player,
row_number() over (partition by t.name order by score desc) as rd
from game
) a
on g.id_player = a.id_player
and g.id_tournament = a.id_tournament
and a.rd=1
order by t.name, g.score desc
Assuming what you want as "Display high score of each player in each tournament"
your query would be like below in MS Sql server
select
t.name as tournament_name,
p.name as Winner,
Max(g.score) as [Highest_Score]
from Tournmanents t
Inner join Game g on t.id_tournament=g.id_tournament
inner join Players p on p.id_player=g.id_player
group by
g.id_tournament,
g.id_player,
t.name,
p.name
Please check this if this works for you
SELECT tournemntData.id_tournament ,
tournemntData.name ,
dbo.Players.name ,
tournemntData.Score
FROM dbo.Game
INNER JOIN ( SELECT dbo.Tournaments.id_tournament ,
dbo.Tournaments.name ,
MAX(dbo.Game.score) AS Score
FROM dbo.Game
INNER JOIN dbo.Tournaments ONTournaments.id_tournament = Game.id_tournament
INNER JOIN dbo.Players ON Players.id_player = Game.id_player
GROUP BY dbo.Tournaments.id_tournament ,
dbo.Tournaments.name
) tournemntData ON tournemntData.id_tournament =Game.id_tournament
INNER JOIN dbo.Players ON Players.id_player = Game.id_player
WHERE tournemntData.Score = dbo.Game.score
I have 3 tables:
Person (with a column PersonKey)
Telephone (with columns Tel_NumberKey, Tel_Number, Tel_NumberType e.g. 1=home, 2=mobile)
xref_Person+Telephone (columns PersonKey, Tel_NumberKey, CreatedDate, ModifiedDate)
I'm looking to get the most recent (e.g. the highest Tel_NumberKey) from the xref_Person+Telephone for each Person and use that Tel_NumberKey to get the actual Tel_Number from the Telephone table.
The problem I am having is that I keep getting duplicates for the same Tel_NumberKey. I also need to be sure I get both the home and mobile from the Telephone table, which I've been looking to do via 2 individual joins for each Tel_NumberType - again getting duplicates.
Been trying the following but to no avail:
-- For HOME
SELECT
p.PersonKey, pn.Phone_Number, pn.Tel_NumberKey
FROM
Persons AS p
INNER JOIN
xref_Person+Telephone AS x ON p.PersonKey = x.PersonKey
INNER JOIN
Telephone AS pn ON x.Tel_NumberKey = pn.Tel_NumberKey
WHERE
pn.Tel_NumberType = 1 -- e.g. Home phone number
AND pn.Tel_NumberKey = (SELECT MAX(pn1.Tel_NumberKey) AS Tel_NumberKey
FROM Person AS p1
INNER JOIN xref_Person+Telephone AS x1 ON p1.PersonKey = x1.PersonKey
INNER JOIN Telephone AS pn1 ON x1.Tel_NumberKey = pn1.Tel_NumberKey
WHERE pn1.Tel_NumberType = 1
AND p1.PersonKey = p.PersonKey
AND pn1.Tel_Number = pn.Tel_Number)
ORDER BY
p.PersonKey
And have been looking over the following links but again keep getting duplicates.
SQL select max(date) and corresponding value
How can I SELECT rows with MAX(Column value), DISTINCT by another column in SQL?
SQL Server: SELECT only the rows with MAX(DATE)
Am sure this must be possible but been at this a couple of days and can't believe its that difficult to get the most recent / highest value when referencing 3 tables. Any help greatly appreciated.
select *
from
( SELECT p.PersonKey, pn.Phone_Number, pn.Tel_NumberKey
, row_number() over (partition by p.PersonKey, pn.Phone_Number order by pn.Tel_NumberKey desc) rn
FROM
Persons AS p
INNER JOIN
xref_Person+Telephone AS x ON p.PersonKey = x.PersonKey
INNER JOIN
Telephone AS pn ON x.Tel_NumberKey = pn.Tel_NumberKey
WHERE
pn.Tel_NumberType = 1
) tt
where tt.rn = 1
ORDER BY
tt.PersonKey
you have to use max() function and then you have to order by rownum in descending order like.
select f.empno
from(select max(empno) empno from emp e
group by rownum)f
order by rownum desc
It will give you all employees having highest employee number to lowest employee number. Now implement it with your case then let me know.
My school task was to get names from my movie database actors which play in movies with highest ratings
I made it this way and it works :
select name,surname
from actor
where ACTORID in(
select actorid
from actor_movie
where MOVIEID in (
select movieid
from movie
where RATINGID in (
select ratingid
from rating
where PERCENT_CSFD = (
select max(percent_csfd)
from rating
)
)
)
);
the output is :
Gary Oldman
Sigourney Weaver
...but I'd like to also add to this select mentioned movie and its rating. It accessible in inner selects but I don't know how to join it with outer select in which i can work just with rows found in Actor Table.
Thank you for your answers.
You just need to join the tables properly. Afterwards you can simply add the columns you´d like to select. The final select could be looking like this.
select ac.name, ac.surname, -- go on selecting from the different tables
from actor ac
inner join actor_movie amo
on amo.actorid = ac.actorid
inner join movie mo
on amo.movieid = mo.movieid
inner join rating ra
on ra.ratingid = mo.ratingid
where ra.PERCENT_CSFD =
(select max(percent_csfd)
from rating)
A way to get your result with a slightly different method could be something like:
select *
from
(
select name, surname, percent_csfd, row_number() over ( order by percent_csfd desc) as rank
from actor
inner join actor_movie
using (actorId)
inner join movie
using (movieId)
inner join rating
using(ratingId)
(
where rank = 1
This uses row_number to evaluate the "rank" of the movie(s) and then filter for the movie(s) with the highest rating.