I need some help I have been scouring the web and haven't been able to find something too similar. I have a MYSQL database for my Golf League. I need to display standings by creating a view from this database. There are 2 people per team, my primary key in 'players' is 'id' there is also a teamID (numerical value 1 - 20, 20 teams) for each player which corresponds to their teammates. Basically what I need is a view that contains 'teamID', both players 'LName' (maybe an 'LNameA','LNameB'), and a sum of the two players 'points' field. I have never summed a field from one person and another or created a view in MYSQL.
EDIT:
I was trying something like
CREATE
VIEW standings1
AS SELECT teamID, LName, points
FROM players
but need teamID to be the primaryKey of the view which will contain each players last name, and their points summed together.
Try this:
create view standings as
select teamId, group_concat(lname separator ', ') as TeamMembers,
sum(points) TotalPoints from players
group by teamId
Oh, one more thing. If you want to have the names of the players in different fields (group_concat just separate them by commas, but it is still a single field) you can use this query:
create view standings as
select a.teamId, a.lname as player1, b.lname as player2,
a.points + b.points TotalPoints
from players a
join players b ON a.teamId = b.teamId AND a.id >= b.id
group by a.teamId, a.id
having count(*) = 2
That way you can play better with the names in PHP without having to parse the ", "
If I understand your table structure, you will need a JOIN against the table's own teamID. I'm assuming the teamID refers to a team, and is not the id of the player. The trick here is to join two copies of the table on the same teamID, but where the player ids are non-equal. That should produce the pair of players per team.
CREATE VIEW standings AS
(
SELECT
p1.teamID AS teamID,
p1.id AS p1id,
p2.id AS p2id,
p1.LName AS p1LName,
p2.LName AS p2LName,
p1.score + p2.score AS totalScore
FROM
/* JOIN on matching teamID and non-matching player-id (so you don't get the same player twice) */
players p1 JOIN players p2 ON p1.teamID = p2.teamID and p1.id <> p2.id
);
Related
I got this last task before I can go to bed...
Make a query that shows the name(not the id) of players who have won the lottery more than once, how many times they've won and the name(not the id) of the municipality they live in.
Players-table: PlayerNum, Name, Address, MunicipalityID
Winners-table: PlayerNum, DrawID
Municipality-table: MunicipalityID, County, Population, Name
Thank you sooo much in advance!!
You need to join the tables and do a sub query on the winner table using count and group by the join the result set with player
Not sure what the draw table does
You really should make an attempt instead of just asking for the solution.
Your starting point is to find the users who have won more than once. This is a simple GROUP BY of PlayerNum and the HAVING clause to limit the result based on the COUNT -
SELECT PlayerNum, COUNT(DrawID) AS num_wins
FROM Winners
GROUP BY PlayerNum
HAVING num_wins > 1
The next step is to add the names of the players. For this you need to join to the Players table and I have added table aliases (w & p) to avoid retyping the full table name each time -
SELECT p.Name, COUNT(DrawID) AS num_wins
FROM Winners w
INNER JOIN Players p
ON w.PlayerNum = p.PlayerNum
GROUP BY w.PlayerNum
HAVING num_wins > 1
And then finally the join to Municipality to get the Name with a column alias as we already have a Name column -
SELECT p.Name, COUNT(DrawID) AS num_wins, m.Name AS MunName
FROM Winners w
INNER JOIN Players p
ON w.PlayerNum = p.PlayerNum
INNER JOIN Municipality m
ON p.MunicipalityID = m.MunicipalityID
GROUP BY w.PlayerNum
HAVING num_wins > 1
So I have the following table structure for a Sports Event system
TEAMS TABLE
team_id
game_id
team_name
team_logo
PLAYERS TABLE
player_id
team_id
player_name
player_mobile
player_email
So whenever a player submits a team registration details get saved on both tables. Events could be something like Cricket, Basketball, Netball, etc. Sometimes they dont fill in players details and sometimes they resubmit their team again which means same team name is submitted.
So whenever I need to check the accurate details of the team list I have been using this:
SELECT team_id FROM `teams` WHERE `game_id`= 35 GROUP BY `team_name
To get a list of the people in these teams that are the same name I was using this:
SELECT team_id, player_name FROM `player` WHERE team_id IN (SELECT team_id FROM `teams` WHERE `game_id`= 35 GROUP BY `team_name`) AND player_name IS NOT NULL AND player_name <> ''
The problem is the query on top gives me different results to what I am getting on the bottom. What I need to do is to get a list of current teams whenever i need. Duplicates of teams should be not there. Then I need a list of the players of these teams.
Currently stumped :( Help me pls.
TL;DR
You can get the desired results with a JOIN and DISTINCT
SELECT DISTINCT t.team_name, P.player_name
FROM teams AS t
INNER JOIN Players AS p
ON p.team_id = t.team_id;
FULL EXPLANATION
The following query is not deterministic, that is to say, you could run the same query on the same data multiple times and get different results:
SELECT team_id
FROM `teams`
WHERE `game_id`= 35
GROUP BY `team_name`;
Many DBMS would not even allow this query to run. You have stated that some teams are duplicated, so consider the following dummy data:
team_id team_name game_id
------------------------------------
1 The A-Team 35
2 The A-Team 35
3 The A-Team 35
When you group by team_name you are end up with one group, so if we start with a valid query:
SELECT team_name
FROM `teams`
WHERE `game_id`= 35
GROUP BY `team_name`;
We would expect one result:
team_name
--------------
The A-Team
When you add team_id in to the select, with no aggregate function, you need to pick one value for team_id, but the query engine has 3 different values to chose from, and none of them are more correct than any other. This is why anything in the select statement, must be contained within the group by (or functionally dependent on something that is), or part of an aggregate function.
The MySQL Docs state:
In standard SQL, a query that includes a GROUP BY clause cannot refer to nonaggregated columns in the select list that are not named in the GROUP BY clause. For example, this query is illegal in standard SQL because the name column in the select list does not appear in the GROUP BY:
SELECT o.custid, c.name, MAX(o.payment)
FROM orders AS o, customers AS c
WHERE o.custid = c.custid
GROUP BY o.custid;
For the query to be legal, the name column must be omitted from the select list or named in the GROUP BY clause.
MySQL extends the use of GROUP BY so that the select list can refer to nonaggregated columns not named in the GROUP BY clause. This means that the preceding query is legal in MySQL. You can use this feature to get better performance by avoiding unnecessary column sorting and grouping. However, this is useful primarily when all values in each nonaggregated column not named in the GROUP BY are the same for each group.
The reason this clause exists is valid, and can save some time, consider the following query:
SELECT t.team_id, t.team_name, COUNT(*) AS Players
FROM teams AS t
LEFT JOIN Players AS p
ON p.team_id = t.team_id
GROUP BY t.team_id;
Here, we can include team_name in the select list even though it is not in the group by, but we can do this safely since team_id is the primary key, therefore it would be impossible to have two different values of team_name for a single team_id.
Anyway, I digress, the problem you are most likely having is that the value returned for team_id in each of your queries will likely be different depending on the context of the query and the execution plan chosen.
You can get a distinct list of players and teams using DISTINCT:
SELECT DISTINCT t.team_name, P.player_name
FROM teams AS t
INNER JOIN Players AS p
ON p.team_id = t.team_id;
This is essentially a hack, and while it does remove duplicate records it does not resolve the underlying issue, of duplicate records, and potentially a sub-optimal data structure.
If it is not too late, I would reconsider your design and make a few changes. If team names are supposed to be unique, then make them unique with a unique constraint, so instead of working around duplicate entries, you prevent them completely.
You should probably be using junction tables for players and games, i.e. have your main tables
Team (team_id, team_name, team_logo etc)
Game (game_id, game_name, etc)
Player (player_id, player_name, player_email, player_mobile etc)
Then tables to link them
Team_Game (team_id, game_id)
Team_Player (team_id, player_id)
This then allows one player to play for multiple teams, or one team to enter multiple events.
Select t.team_id , p.player_name from player p
JOIN teams t
ON t.team_id = p.team_id
Where t.game_id = 35 AND p.player_name IS NOT NULL AND p.player_name <> ''
GROUP BY(t.team_name)
```
You should do a unique constraint on the team_name column, this way you are not allowing duplicate teams
Ps. I did not test the query but it should work
SELECT
player.FirstName,
player.LastName,
team.teamName,
TotalPoints,
TotalRebounds,
TotalAssists,
TotalSteals,
TotalBlocks
FROM playerstats
INNER JOIN player
ON playerstats.PlayerID = player.PlayerID
I have a table called player (Player ID, firstname, lastname, team ID)
table called Team (teamID, teamName). I have a table called playerstat(which has playerID)
I want to list firstname, last name and team along with total points, rebounds, etc
I want to use the playerID to get the team Id then list the team name ... if that makes sense. Not sure how to do that.
In your question, you don't indicate if the playerstats table has multiple rows per player, and you don't indicate what the team table's columns might be, but presuming that the playerstats table has multiple rows per player, and that you have a team table, you might give this a try. You will need to substitute the correct column names:
SELECT
player.FirstName,
player.LastName,
team.teamName,
sum(points) as TotalPoints,
sum(rebounds) as TotalRebounds,
sum(assists) as TotalAssists,
sum(steals) as TotalSteals,
sum(blocks) as TotalBlocks
FROM playerstats
INNER JOIN player
ON playerstats.PlayerID = player.PlayerID
JOIN team
ON team.id = player.teamID
GROUP BY player.FirstName, player.LastName,team.teamName
ORDER BY player.FirstName, player.LastName,team.teamName;
Select P.FirstName,P.LastName,t.teamName,s.TotalPoints
from Player P
join Team t on P.TeamId=t.TeamId
join playerstats s on P.PlayerId=s.PlayerId
I have a table for the football clubs of a country. The fields are "teamName", "playerName", and "country".
I'd like to count the clubs that all their players are foreigners
. I tried the following query but I think it's not working since it seems that it counts when we have at least one foreigner but I want it to count if all the players of a team are foreigners!
SELECT COUNT(DISTINCT teamName)
FROM teams
WHERE country not like '%England%'
Please advise. Thanks!
One way would be:
SELECT COUNT(DISTINCT teamName)
FROM teams T1
WHERE NOT EXISTS
( select * from teams T2
WHERE T1.teamName=T2.teamName and T2.country like '%England%')
Hmm even join seems to need an inner query:
SELECT COUNT(*)
FROM (
SELECT teamName,
SUM(country like '%England%') AS Locals
FROM teams
GROUP BY teamName
) AS t
WHERE Locals = 0;
Seems like there should be a shorter answer though...
Quick and dirty answer, and it does only one pass through the data, no subquery. This selects teams that are all foreign. You can play with the CASE expression if that is not what you want.
SELECT team_name
FROM teams
GROUP BY team_name
HAVING COUNT(country)=
SUM(CASE country != 'England' WHEN TRUE THEN 1 ELSE 0 END);
Longer answer: Your schema is not normalized, but should be. You want want table of teams and a second table of players, which includes a foreign key into the team table for that player's current team. This is basic DB normalization. However, replacing the single table in the FROM with the join of those two tables, the same GROUP BY/HAVING trick works.
I am quite new on SQL and I am trying to practice to improve myself.
I have a database which has a
Table : Players, Teams, Plays, and Wins
Players : pid, pname, age, country
Plays : pid, season, tid, value ( pid -> pid in Players, tid -> tid in Teams )
Teams : tid, tname, tcolor, tbudget
Wins : wtid, ltid, season, wscore, lscore ( wtid,ltid -> tid in Teams )
The question is Find the name of the players whose played in atleast 2 dif. teams with same color
What I did is
SELECT DISTINCT P.pname
FROM Players P
,Teams T1
GROUP BY T1.tcolor
HAVING 1 < (
SELECT COUNT (10)
FROM Teams T2
WHERE T1.tcolor=T2.tcolor)
When I try to query this , I get an error which is ;
Error Code: 1630
FUNCTION PRALATEST.COUNT does not exist. Check the 'Function Name Parsing and Resolution' section in the Reference Manual
In which part am I doing wrong?
Try this:
select pname
from Players
join Plays on Plays.pid = Players.pid
join Teams on Teams.tid = Plays.tid
group by pname, tcolor
having count(Teams.tname) > 1
The condition count(Teams.tname) > 1 is in a having clause instead of a where clause becuase it needs to operate on the results AFTER the group by is performed.
Couple things. Your error message is because you put a numeric constant in the COUNT function. You should just use an asterisk.
Also, you have not specified a join condition for your Players and Teams tables. As a result, you are doing a product join (probably not what you want). I'm guessing you need to join to your Plays table.
You should change your coding practice to use "explicit" join syntax to avoid errors like this in the future.