I'm using the code below to calculate the total score for my teams :
My tables are also listed bellow .
The problem is that the scores are being incorrectly calculated for every team except the first one . The image should explain the desired outcome based on the info in my database.
Query :
mysqli_query($connection, "UPDATE teams SET totalscore=overall_score+IFNULL((SELECT sum(overall_user_score) FROM users WHERE team_id=id),0)") or die(mysqli_error($connection));
Tables :
users(name, team_id, overall_user_score)
teams(id, name, team_score, totalscore)
Image:
I'm not sure why you have overall_score and totalscore as two different columns, but anyways:
If you are summing the totalscore column based on the overall_user_score column from the users table, you don't need to keep adding overall_score (in the teams table) to the totalscore column. See here as an example.
Again, I'm not sure why you have both overall_score and totalscore as two different columns. If I'm misunderstanding the question, let me know.
Really stupidly left out the t. infront of the last id so query should be :
mysqli_query($connection, "UPDATE teams t SET totalscore=overall_score+IFNULL((SELECT sum(overall_user_score) FROM users WHERE team_id=t.id),0)") or die(mysqli_error($connection));
Related
Ok, i'm drawing a blank here and in dire need of your help!
3 tables:
matches (id, goals_slot_1, goals_slot_2, won, draw)
teams (id, name, score_for, score_against, won, lost, draw, points)
team-match (junction table) (team_id, match_id)
So what i want to achieve, is to update the 'draw' column in the teams table SET to the 'sum(draw)' of the matches table of the according teams.
The value of 'draw' in the matches table is '1' when it's a draw, '0' when not.
I just can't figure it out anymore. Stuck on it for days...
Can someone put me on the right track?
You would need to use a correlated sub query to get the values from the other tables. Something like:
UPDATE `teams`
SET `draw`=(SELECT SUM(`draw`)
FROM `matches`
WHERE `id` IN (SELECT `match_id`
FROM `team-match`
WHERE `team_id`=`teams`.`id`))
Or even a single sub query with a join:
UPDATE `teams`
SET `draw`=(SELECT SUM(`draw`)
FROM `matches`
JOIN `team-match`
ON `team-match`.`match_id`=`matches`.`id`
WHERE `team-match`.`team_id`=`teams`.`id`)
Both should do the work. I would assume the first is better for performance, but haven't tested and really they should be within a few milliseconds of each other. Other than this, you would need to use php to query the values and update the individual rows. Really though, the won/lost/draw columns could be calculated on the fly with similar performance and you wouldn't have to update the values every match.
I have a voting script which pulls out the number of votes per user.
Everything is working, except I need to now display the number of votes per user in order of number of votes. Please see my database structure:
Entries:
UserID, FirstName, LastName, EmailAddress, TelephoneNumber, Image, Status
Voting:
item, vote, nvotes
The item field contains vt_img and then the UserID, so for example: vt_img4 and both vote & nvotes display the number of votes.
Any ideas how I can relate those together and display the users in order of the most voted at the top?
Thanks
You really need to change the structure of the voting table so that you can do a normal join. I would strongly suggest adding either a pure userID column, or at the very least not making it a concat of two other columns. Based on an ID you could then easily do something like this:
select
a.userID,
a.firstName,
b.votes
from
entries a
join voting b
on a.userID=b.userID
order by
b.votes desc
The other option is to consider (if it is a one to one relationship) simply merging the data into one table which would make it even easier again.
At the moment, this really is an XY problem, you are looking for a way to join two tables that aren't meant to be joined. While there are (horrible, ghastly, terrible) ways of doing it, I think the best solution is to do a little extra work and alter your database (we can certainly help with that so you don't lose any data) and then you will be able to both do what you want right now (easily) and all those other things you will want to do in the future (that you don't know about right now) will be oh so much easier.
Edit: It seems like this is a great opportunity to use a Trigger to insert the new row for you. A MySQL trigger is an action that the database will make when a certain predefined action takes place. In this case, you want to insert a new row into a table when you insert a row into your main table. The beauty is that you can use a reference to the data in the original table to do it:
CREATE TRIGGER Entries_Trigger AFTER insert ON Entries
FOR EACH ROW BEGIN
insert into Voting values(new.UserID,0,0);
END;
This will work in the following manner - When a row is inserted into your Entries table, the database will insert the row (creating the auto_increment ID and the like) then instantly call this trigger, which will then use that newly created UserID to insert into the second table (along with some zeroes for votes and nvotes).
Your database is badly designed. It should be:
Voting:
item, user_id, vote, nvotes
Placing the item id and the user id into the same column as a concatenated string with a delimiter is just asking for trouble. This isn't scalable at all. Look up the basics on Normalization.
You could try this:
SELECT *
FROM Entries e
JOIN Voting v ON (CONCAT('vt_img', e.UserID) = v.item)
ORDER BY nvotes DESC
but please notice that this query might be quite slow due to the fact that the join field for Entries table is built at query time.
You should consider changing your database structure so that Voting contains a UserID field in order to do a direct join.
I'm figuring the Entries table is where votes are cast (you're database schema doesn't make much sense to me, seems like you could work it a little better). If the votes are actually on the Votes table and that's connected to a user, then you should have UserID field in that table too. Either way the example will help.
Lets say you add UserID to the Votes table and this is where a user's votes are stored than this would be your query
SELECT Users.id, Votes.*,
SUM(Votes.nvotes) AS user_votes
FROM Users, Votes
WHERE Users.id = Votes.UserID
GROUP BY Votes.UserID
ORDER BY user_votes
USE ORDER BY in your query --
SELECT column_name(s)
FROM table_name
ORDER BY column_name(s) ASC|DESC
I currently have two tables in which stores the attendances of a student in a course. I have the hub_attendance table which stores the total attendances of a student and the hub_attendance_lesson where it stores the attendance of each lesson that a student has or has not attended. I'm not sure if this is correct or if I'm doing anything wrong, I'm a beginner in databases!
hub_attendance:
id
student_id
course_id
total_lessons
total_lessons_so_far
total_attended
total_absent
total_excused_absent
total_late
total_excused_late
hub_attendance_lesson:
id
lesson_id
course_id
student_id
date
attended
absent
excused_absent
late
excused_late
EDIT:
So I've gotten rid of the first table completely and this is my new single table.
Hub_Attendance:
id
lesson_id
course_id
student_id
date
attendance
As Dutchie432 said, you don't need the first table because it introduces unnecessary redundancy and you can count those statistics on the fly. Such aggregate tables can be a good solution if performance is an issue, but they should be used only as a last resort.
About the second table - you have separate fields attended, absent, excused_absent,
late and excused_late. Aren't these mutually exclusive? So only one of them can be true for one row? If so, you may be better off with one enumeration field called for example attendance, which would take different values for each of those states. In that way you could't have rows where none of the flags, or more than one flag, is set.
Here's what you need:
**Course**
id, name, etc...
**Lesson**
id, courseid, name, etc...
**Attendance**
id, studentid, lessonid, lateness, etc...
**Enrolment**
id, courseid, studentid, startdate, etc...
You need the enrolment table to know that students should be on a course even if they never turn up for lessons. The attendance table will allow you to have many students per lesson and many lessons per student. This is a many-to-many table. Any aggregation and counting can be done in SQL.
If I understand your schema correctly, Your first table can be totally eliminated. You should be able to fetch the totals using MySQL.
select count(id) as total_late from hub_attendance_lesson where late=true and student_id=TheUserId
Remove this first table, every total can be fetch using SQL :
SELECT count(id) AS absent
FROM hub_attendance_lesson
WHERE lesson_id = <your lesson id>
AND absent = <false / true>
I guess you'll be able to adapt this code for your needs.
I'm trying to record test/quiz scores in a database. What's the best method to do this when there might be a lot of tests and users?
These are some options I considered: should I create a new column for each quiz and row for users, or does this have its limitations? Might this be slow? Should i create a new row for each user & quiz? Should I stick to my original 'user' database and encode it in text?
Elaborating a little on the plan: JavaScript Quiz, submits score with AJAX, and a script sends it to the database. I'm new with php so i'm not sure about a good approach.
Any help would be greatly appreciated :) this is for a school science fair
I'd suggest 3 data tables in your database: students, tests, and scores.
Each student needs to have fields for an ID and whatever else (name, dob, etc) you want to record about them.
Tests should have fields for an ID and whatever else (name, date, weight, etc).
Scores should have the student ID, a test ID, and the score (any anything else).
This means you can query a student and join with the scores table to get all the student's scores. You can also join the test table these results to get labels put onto each score and calculate a grade based on scores and weight.
Alternately you can query for a test and join with the scores to get all the scores on a given test to get the class stats.
I would say create a database table, maybe one that lists all students(name, dob, student id), and then one for all tests(score, date, written by). Will only you access the db, or can your students access it too? If the latter is the case, you need to make sure the create accurate security or "views" to ensure the student can only see their own grades at a time (not everyone's).
Definitely do not create dynamic columns! (no column for each quiz). Also adding columns to user table (or generally any table) when they are not identifying the user(or generally any table item) is bad aproach...
This is pretty example of normalization, you should avoid storing any redundant rows. To do that you would create 3 tables and foreign keys to ensure scores are always referencing an existing user and quiz. E.g.:
users - id, nickname, name
quizzes - id, quizName, quizOtherData
scores - id, user_id (references users.id) , quiz_id , (ref. quizzes.id), score
And then add rows to scores table per user per quiz. Additionaly you could create UNIQUE key for columns user_id and quiz_id to disallow users to complete one quiz more times than one.
This will be fast and will not store redundant (unneeded extra) data.
To get results of quiz with id e.g. 4 and user info of people who's submitted this quiz, ordered from highest to lowest score, you would do query like:
SELECT users.*, scores.score
FROM scores RIGHT JOIN users ON(users.id=scores.user_id)
WHERE scores.quiz_id = 4
ORDER BY score DESC
Reason why I used RIGHT join here is because there might be users that didn't do this quiz, however every score always have an existing user&quiz (due to foreign keys
To get overall info of all users, quizes and scores you would do something like:
SELECT *
FROM quizzes
LEFT JOIN scores ON(quizzes.id=scores.quiz_id)
LEFT JOIN users ON(users.id=scores.user_id)
ORDER BY quizzes.id DESC, scores.score DESC, users.name ASC
BTW: If you are new to PHP (or anybody reading this), use PHP's PDO interface to communicate with your database :) AVOID functions like mysql_query, at least use mysqli_query, but for portability I would recommend stay with PDO.
I need to know how to handle a pretty complex situation.
I have a system that allows users to vote up or down on comments that others make. I want to create a report of those with the most up votes based on all of their comments. The upvotes were not tracked in the users table, only in the comments table so it needs to go through the comments table and get the value in the vote column and output the sum of all of the vote column values for each userid. It then needs to order these and output the top 10.
Thanks in advance for help
If you post your users and comments table structure I could make a query. But it would be something like this:
SELECT SUM(votes) total, user_id FROM comments GROUP BY user_id ORDER BY total LIMIT 10