SELECT Count(Teams.Name)
, Teams.TeamID
, Teams.Name
FROM Teams, Rosters
WHERE Rosters.TeamID = Teams.TeamID
Is my query so far. I'd like it to print the number of entries of Rosters.TeamID that correspond to Teams.TeamID.
I think the query you want is:
SELECT t.TeamID, t.Name, COUNT(*)
FROM Teams t JOIN
Rosters r
ON r.TeamID = t.TeamID
GROUP BY t.TeamID, t.Name;
Basically, your query is missing the GROUP BY, but you should also learn proper JOIN syntax.
Related
I'm having a problem in where i want to count how many medals in total a country has won from both the individual and team competitions does not give me the disered outcome. i have managed so far tocome up with this.
select distinct C.Cname as Country, count(i.medal) as Medals_Won
from individual_results as i, Country as C, participant as p
where (i.Olympian = p.OlympicID and C.Cname = p.country)
union
select distinct C.Cname, count(r.medal) as medals_Won
from team_results as r, Country as C, participant as p, team as t
where (r.team = t.TeamID and t.Member1 = p.OlympicID and C.Cname = p.Country)
group by C.Cname
order by medals_won desc
enter image description here
but i get this result.
even tho if i run the two separate pieces of code i ge the wanted restuls that is enter image description here
You say you can run your query and it gives you a result. This is bad. It indicates that you are MySQL's notorious cheat mode that lets you run invalid queries.
You have something like this:
select ...
union
select ...
group by ...
order by ...
There are two queries the results of which you glue together, namely
select ...
and
select ...
group by ...
So, your first query becomes:
select distinct C.Cname as Country, count(i.medal) as Medals_Won
from individual_results as i, Country as C, participant as p
where (i.Olympian = p.OlympicID and C.Cname = p.country)
You COUNT medals, i.e. you aggregate your data. And there is no GROUP BY clause. So you get one result row from all your data. You say you want to count all rows for which i.medal is not null. But you also want to select the country. The country? Which??? Is there just one country in the tables? And even then your query would be invalid, because still you'd have to tell the DBMS from which row to pick the country. You can pick the maximum country (MAX(C.Cname)) for instance or the minimum country (MIN(C.Cname)), but not the country.
The DBMS should raise an error on this invalid query, but you switched that off.
Make sure in MySQL to always
SET sql_mode = 'ONLY_FULL_GROUP_BY';
It is the default in more recent versions, so either you are working with old software or you switched from good mode to bad mode voluntarily.
And talking of old software: Even at the first moment MySQL was published, comma joins had long been deprecated. They were made redudant in 1992. Please don't ever use commas in your FROM clause. Use explicit joins ([INNER] JOIN, LEFT [OUTER] JOIN, etc.) instead.
As to the task, here is a straight-forward solution with joins:
select
c.cname as country,
coalesce(i.medals, 0) as medals_individual,
coalesce(t.medals, 0) as medals_team,
coalesce(i.medals, 0) + coalesce(t.medals, 0) as medals_total
from country c
left outer join
(
select p.country, count(ir.medal) as medals
from participant p
join individual_results ir on ir.olympian = p.olympicid
group by p.country
) i on on i.country = c.name
left outer join
(
select p.country, count(ir.medal) as medals
from participant p
join team t on t.member1 = p.olympicid
join team_results tr on tr.team = t.teamid
group by p.country
) t on on t.country = c.name
order by medals_total desc;
You should sum the union result for each of the subquery grouped by cname
select t.Cname , sum( t.Medals_Won)
from (
select C.Cname as Country, count(i.medal) Medals_Won
from individual_results i
inner join participant p ON i.Olympian = p.OlympicID
inner join Country C ON C.Cname = p.country
group by C.Cname
union
select distinct C.Cname, count(r.medal)
from team_results as r
inner join team as t ON r.team = t.TeamID
inner join participant as p ON t.Member1 = p.OlympicID
inner join Country as C ON C.Cname = p.Country
group by C.Cname
) t
group by t.Cname
order by sum( t.Medals_Won) desc
I have two tables: match(id.match, date, home, away) and team(id. team, name). In match home and away are foreign keys to the team id. In my query, I want an output record with date of match, and name of these two teams.
I have tried:
SELECT m.date, m.home, m.away, t.name
FROM `match` m
JOIN team t ON m.home = t.id_team
ORDER BY m.date
But this outputs two records instead of one. Is it possible to do what I want with sql or I should just change the table's design?
I suspect you have a many to one relationship between your tables.
This might work depending on the table values:
SELECT DISTINCT m.date, m.home, m.away, t.name
FROM `match` m JOIN
team t ON m.home = t.id_team
ORDER BY m.date
Ok, i did 'deeper' research and find out the answer. Earlier i just asked wrong question. Thanks everyone for contribution!
Here is the solution:
SELECT m.date, m.home, m.away, t.name AS homename, te.name AS awayname
FROM `match` m
JOIN team t ON m.home = t.id_team
JOIN team te
ON m.away = te.id_team ORDER BY m.date
I'm having huge difficulty with a 3 table query.
The scenario is that TEAM has many or no MEMBERS, a MEMBER could have many or no TASKS. What I want to get is the number of TASKS for every TEAM. TEAM has its own ID, MEMBER holds this as a FK on TEAM_ID, TASK has MEMBER_ID on the TASK.
I want to get a report of TEAM.NAME, COUNT(Person/Team), Count(Tasks/Team)
I have myself so confused, My thinking was to use an Outer Join on TEAM and MEMBER so I have all the teams with any members they have. From here I'm getting totally confused. If anyone can just point me in the right direction so I have something to work from I'd be so greateful
You want to use count distinct:
MySQL COUNT DISTINCT
select t.name as Team,
count(distinct m.ID) as Member_cnt,
count(distinct t.ID) as Task_cnt
from team t
left join member m
on t.ID= m.TEAM_ID
left join tasks t
on t.MEMBER_ID= m.ID
group by t.name;
I think you can do what you want with aggregation -- and count(distinct):
select t.name,
count(distinct m.memberid) as nummembers,
count(distinct tk.taskid) as numtasks
from team t left join
member m
on t.teamid = j.teamid left join
tasks tk
on tk.memberid = m.memberid
group by t.name;
Try this out :
SELECT Team.name, COUNT(Person.id_person), COUNT(Tasks.id_task)
FROM Team t,
LEFT JOIN Person p on p.team_id = t.id_team
LEFT JOIN Tasks ts on ts.person_id = p.id_person
GROUP BY p.team_id, ts.person_id
It works but what I would like is to list username, first name, last name not all but I've tried JOIN and isn't seeming to work. Any ideas? Thanks!
MY DB:
http://gyazo.com/eb13cd68440d20719ce0783018cb9828
SELECT
M.Username,
M.first_name,
M.Last_name,
COUNT(1) AS num_comments
FROM members AS M
INNER JOIN comments AS C
ON C.memberID = M.memberID
GROUP BY
C.memberID
ORDER BY COUNT(1) DESC
LIMIT 1
This matches the Member to all their comments, groups by the member to get the count of comments for the users, orders by the count starting highest first, then returns the first result.
Instead of selecting * (ALL) just use SELECT table.username, table.firstname, table.lastname [...].
You can leave out the table. if all information is stored in your comments table. If not, adjust accordingly. In that case you'll also need to Join the comments table with the table where the rest of the information is stored.
Edit:
SELECT m.username, m.first_name, m.last_name FROM members m, comments c WHERE m.MemberID = c.MemberID AND c.author = (select max(author) from comments)
How could I find the most common value in table player_frags of either lasthit or mostdamage and order by asc?
SELECT DISTINCT(name) FROM players p
INNER JOIN player_frags pf ON pf.lasthit = p.name
OR pf.mostdamage = p.name
SELECT name FROM players p
INNER JOIN player_frags pf ON pf.lasthit = p.name
OR pf.mostdamage = p.name GROUP BY name Order By COUNT(*) DESC
You could add LIMIT 1 at the end for the most common name.
SQL Fiddle
I don't think you tried, this looks exactly like the other SQL you posted in the other question you sent
Anyway this will return name vs frequency of appearing:
SELECT COUNT(*) AS Freq, name
FROM players
GROUP BY players.name
ORDER BY COUNT(*)