maybe you can help me. I actually study SQL on ORACLE Platform and i have several exercises.
One of them is to hard for me, i don´t get it done right...
This is the Excercise:
Which Countrys are member in ALL organisations, where also Country XY is member of?
I have multiple tables but i think only one is necessary for this task.
Tablename: isMember ( abbreviation(fk), country(fk) )
So the Tables looks like:
Country / Abbreviation
USA / G-5
USA / G-7
USA / G-9
Canada / G-7
Canada / G-9
Norway / G-20
and so on....
How can i find every country in the list which is also member of ALL organizations where for example USA is member of?
Thank you very much!
This is a tricky question. One method is to construct all rows with countries and organization the US is in. Then, count the number each country has and see if they match:
select c.country
from (select distinct country from isMember) c cross join
(select abbreviation from isMember where country = 'USA') a left join
isMember im
on im.country = c.country and im.abbreviation = a.abbreviation
group by c.country
having count(*) = count(im.country); -- do all organizations match?
Related
I'm starting with SQL and doing some exercises and I'm completely stuck on the last one.
It is about looking for streets in the same country name. Two tables are used, locations and countries from the HR schema.
The problem is that I don't know how to avoid duplicate results. For example if I have the street "x" in Canada and the street "y" also in Canada, it shows me twice:
street x / Canada / street y
street y / Canada / street x
and I can't find a way to correct this.
My select is:
SELECT DISTINCT A.STREET_ADDRESS AS "CALLE A", C.COUNTRY_NAME, B.STREET_ADDRESS AS "CALLE B"
FROM HR.LOCATIONS A JOIN HR.LOCATIONS B ON (A.STREET_ADDRESS <> B.STREET_ADDRESS), HR.COUNTRIES C
WHERE A.COUNTRY_ID = B.COUNTRY_ID AND B.COUNTRY_ID = C.COUNTRY_ID
ORDER BY C.COUNTRY_NAME
I get this Result_
Any ideas? Thank you.
use < instead of <>
SELECT DISTINCT A.STREET_ADDRESS AS "CALLE A", C.COUNTRY_NAME, B.STREET_ADDRESS AS "CALLE B"
FROM HR.LOCATIONS A JOIN HR.LOCATIONS B ON (A.STREET_ADDRESS > B.STREET_ADDRESS), HR.COUNTRIES C
WHERE A.COUNTRY_ID = B.COUNTRY_ID AND B.COUNTRY_ID = C.COUNTRY_ID
ORDER BY C.COUNTRY_NAME
All the correct answers should be logically equivalent. You may want to use a form closer to this, however.
Ignore the alignment, unless you feel it helps readability (I happen to).
I'm referring more to the JOIN / ON form (avoid comma separated table expressions in the FROM clause, called <table reference list> ... a single <table reference> is usually sufficient), as #jarlh mentioned, and to keep the join criteria (in the ON clauses) nearer to the corresponding tables in the FROM clause, unless you have a particular reason to separate any of the logic to the WHERE clause (try to avoid that, unless necessary).
Logically, we can write these in lots of different ways. Some may be a little easier to write/read.
SELECT A.STREET_ADDRESS AS "CALLE A"
, C.COUNTRY_NAME
, B.STREET_ADDRESS AS "CALLE B"
FROM HR.LOCATIONS A
JOIN HR.LOCATIONS B
ON A.COUNTRY_ID = B.COUNTRY_ID
AND A.STREET_ADDRESS < B.STREET_ADDRESS
JOIN HR.COUNTRIES C
ON B.COUNTRY_ID = C.COUNTRY_ID
ORDER BY C.COUNTRY_NAME
;
The inequality, as #nbk points out, avoids the street reflections.
SELECT DISTINCT isn't really needed for this, if your join logic and selected detail is sufficient to identify unique locations. If not, the result probably isn't practically useful.
If this is a small subset of sample data and/or these street addresses are unique within each country, then you're also ok, and DISTINCT isn't needed.
So I have a table with players data(name, team, etc..) and a table with goals (player who scored it, local team, etc...). What I need to do is, get from each team the highest scorer. So the result I'm getting is something like:
germany - whatever name - 1
germany - another dude - 5
spain - another name - 8
italy - one more name - 6
As you can see teams repeat, and I want them not to, just get the highest scorer of each team.
Right now I have this:
SELECT P.TEAM_PLAYER, G.PLAYER_GOAL, COUNT(*) AS "TOTAL GOALS" FROM PLAYER P, GOAL G
WHERE TO_CHAR(G.DATE_GOAL, 'YYYY')=2002
AND P.NAME = G.PLAYER_GOAL
GROUP BY G.PLAYER_GOAL, P.TEAM_PLAYER
HAVING COUNT(*)>=ALL (SELECT COUNT(*) FROM PLAYER P2 where P.TEAM_PLAYER = P2.TEAM_PLAYER GROUP BY P2.TEAM_PLAYER)
ORDER BY COUNT(*) DESC;
I am 100% sure I'm close, and I'm pretty sure I have to do this with the HAVING feature, but I can't get it right.
Without the HAVING it returns a list of all the players, their teams and how many goals have they scored, now I want to cut it down to only one player for each team.
PD: the teams in the table GOAL are local and visiting team, so I have to use the Player table to get the team. Also the Goal table is not a list of the players and how many goals they have scored, but a list of every individual goal and the player who scored it.
If I understand correctly you can try this query.
just get MAX of PLAYER_GOAL column,SUM(G.PLAYER_GOAL) instead of COUNT(*)
SELECT P.TEAM_PLAYER,
MAX(G.PLAYER_GOAL) "PLAYER_GOAL",
SUM(G.PLAYER_GOAL) AS "TOTAL GOALS"
FROM PLAYER P
INNER JOIN GOAL G
ON P.NAME = G.PLAYER_NAME
WHERE TO_CHAR(G.DATE_GOAL, 'YYYY')=2002
GROUP BY P.TEAM_PLAYER
ORDER BY SUM(G.PLAYER_GOAL) DESC;
NOTE :
Avoid using commas to join tables it's a old join style, You can use inner-join instead.
Edit
I don't know your table schema, but this query might be work.
use a subquery to contain your current result set. then get MAX function and GROUP BY
SELECT T.TEAM_PLAYER,
T.PLAYER_GOAL,
MAX(TOTAL_GOALS) AS "TOTAL GOALS"
FROM
(
SELECT P.TEAM_PLAYER, G.PLAYER_GOAL, COUNT(*) AS "TOTAL_GOALS" FROM
PLAYER P, GOAL G
WHERE TO_CHAR(G.DATE_GOAL, 'YYYY')=2002
AND P.NAME = G.PLAYER_GOAL
GROUP BY G.PLAYER_GOAL, P.TEAM_PLAYER
HAVING COUNT(*)>=ALL (SELECT COUNT(*) FROM PLAYER P2 where P.TEAM_PLAYER = P2.TEAM_PLAYER GROUP BY P2.TEAM_PLAYER)
) T
GROUP BY T.TEAM_PLAYER,
T.PLAYER_GOAL
ORDER BY MAX(TOTAL_GOALS) DESC
I am trying to create a report that will return a list of people whose cities most likely need to be corrected.
I was thinking of comparing the data against other data within the table to leverage the assumption that most of the cities are spelled correctly. Take Albuquerque, for example. We have records for many of the zip codes, but the city isn't always spelled correctly.
I can't figure out my next step.
Here's what I have started with:
SELECT city, zip_5_digits, COUNT(*) AS "COUNT"
FROM people
INNER JOIN addresses
ON addresses.people_id = people.id
AND city LIKE 'Albu%que'
GROUP BY city, zip_5_digits
Doing this results in
Albuqureque 87108 1
Albuquerque 87108 238
Albuqerque 87109 1
Albuquerque 87109 34
What I'd like to do is, for each row, find the maximum records where the zip code matches but the city does not match. If there is no match, I want to return that record, and I'll use this to return people's id and names, since I most likely need to correct the name of the city for those people who have it mis-spelled.
This is hard, because some "cities" have very few residents. And, some zip codes might just have a small part of a city.
I would recommend two rules:
Look at zip codes that have at least a certain number of people -- say 100.
Look at cities in the zip code that have less than some number -- say 5.
There are candidates for misspellings:
SELECT pa.*
FROM (SELECT city, zip_5_digits, COUNT(*) AS cnt,
MAX(COUNT(*)) OVER (PARTITION BY zip_5_digits) as max_cnt,
SUM(COUNT(*)) OVER (PARTITION BY zip_5_digits) as sum_cnt
FROM people p, INNER JOIN
addresses a
ON a.people_id = p.id
GROUP BY city, zip_5_digits
) pa
WHERE sum_cnt >= 100 AND cnt <= 5;
I seem to be having problem getting a certain query to work. I know I'm so close. Here's a copy of my er diagram
I think I am so close to achieving what I want to do with this code, only I get invalid identifier when trying to run it. I think its because the practice is being changed somehow after joining, as I am only getting invalid identifier on row 5?
SELECT staffid, staff_firstname, staff_surname, practice.practice_name, practice.practice_city
from staff
join practice on staff.practiceid = practice.practiceid
MINUS
SELECT staffid, staff_firstname, staff_surname, practice.practice_name, practice.practice_city
from staff
where role = 'GP';
Basically I'm trying to use the minus construct to find practices which do not employ a GP and include some information such as the CITY and practice_address.
I can use the minus construct to find out how many staff do not have the role of GP like so:
SELECT staffid, staff_firstname, staff_surname
from staff
MINUS
SELECT staffid, staff_firstname, staff_surname
from staff
where role = 'GP';
where I get the results:
STAFFID STAFF_FIRS STAFF_SURN
__________ __________ __________
8 NYSSA THORNTON
9 MONA BRADSHAW
10 GLORIA PENA
I'm struggling to use the join with the minus construct to get information about the GP's practice address and city etc.
Any help would be greatly appreciated!
The second select, after the minus, is referring to columns from the practice table - but it doesn't join to it:
SELECT staffid, staff_firstname, staff_surname,
practice.practice_name, practice.practice_city
from staff
join practice on staff.practiceid = practice.practiceid
MINUS
SELECT staffid, staff_firstname, staff_surname,
practice.practice_name, practice.practice_city
from staff
join practice on staff.practiceid = practice.practiceid
where role = 'GP';
That isn't going to give you what you want though, it will just remove the rows for staff that are GPs, not all trace of practices that have any GPs - non-GP staff at all practices will still be shown.
if you don't want the remaining staff details you only need to include the columns from the practice table in the select lists, and the minus would then give you what you want (and Gordon Linoff has shown two alternatives to minus in that case). If you do want the remaining staff details then you can use a not-exists clause rather than a minus - something like:
select s.staffid, s.staff_firstname, s.staff_surname,
p.practice_name, p.practice_city
from staff s
join practice p on s.practiceid = p.practiceid
where not exists (
select 1
from staff s2
where s2.practice_id = p.practice_id
and s2.role = 'GP
);
This is similar to Gordon's second query but has an extra join to staff for the details. Again, if you don't want those, use Gordon's simpler query.
You could also use an aggregate check, or could probably do something with an analytic function if you've learned abput those, to save having to hit the tables twice.
Your original query only operates on the level of "staff", not "practice". I would be inclined to solve this using aggregation:
select p.practice_name, p.practice_city
from staff s join
practice p
on s.practiceid = p.practiceid
group by p.practice_name, p.practice_city
having sum(case when s.role = 'GP' then 1 else 0 end) = 0;
Or, even better:
select p.*
from practice p
where not exists (select 1
from staff s
where s.practiceid = p.practiceid and s.role = 'GP'
);
I think this is the simplest and most direct interpretation of your question.
Table Name: REG_NBRS
STATE CITY COUNTRY REG_NBR
------------------------------------------
ILLINOIS USA 444333222
NEBRASKA USA 111222333
NEW YORK USA 333444555
FLORIDA USA 666222666
TAMPA USA 888333888
I have data something like this and I need to get REG_NBR for that state or city. If the row matches both for state and City, city takes precidence, and if it is not matched for either state or city, then I will have to still list the row with null for reg_nbr.
I tried to come up with a query but didn't get much successs as I don't know how to impose a precidence while doing an outer join.
SELECT C.NAME, C.AGE, RN.REG_NBR
FROM CUSTOMER C, REG_NBRS RN
WHERE C.COUNTRY = RN.COUNTRY
AND (C.STATE = RN.STATE OR C.CITY = RN.CITY)
AND C.ID BETWEEN 1000 AND 2000
As a beginner, I do not know how to join these two tables in such a way that
it joins first on STATE and City
But still list all 1000 rows
Put null to those registered numbers which are not from those states or cities
If both match, then use the State's Registered number (i.e. use 666222666 for Tampa even though we can find an entry for TAMPA)
I am sorry if this is not making sense but I have tried to explain as much as possible. I have also tried different combinations of left outer join and right outer join but couldn't get how to impose a hierarchy for WHERE coinditions. I thought of UNIONS but I think even unions would list 2 rows for a customer in Tampa with both REG_NBRs.
Any suggestions?
APOLOGIZE for jumbled code as I am using a (not so) smart phone to post this question.
Assuming that you have unique keys in (Country, State) and (Country, City), you can do it in a simple way by joining twice:
SELECT
C.NAME, C.AGE,
COALESCE(RN1.REG_NBR, RN2.REG_NBR) AS REG_NBR
FROM CUSTOMER C
LEFT OUTER JOIN REG_NBRS RN1
ON RN1.COUNTRY = RN1.COUNTRY
AND RN1.STATE = C.STATE
LEFT OUTER JOIN REG_NBRS RN2
ON RN2.COUNTRY = C.COUNTRY
AND RN2.CITY = C.CITY
WHERE C.ID BETWEEN 1000 AND 2000
Moreover this should be faster than the OR, which databases don't like much (at least with proper indexing in place).