Hi I have a question regarding a method to prevent second voting in a website where people can vote up or vote down a comment. Like Stackoverflow!! :)
The question is how I can keep track of whether a comment has already been voted by a logged in user. Lets assume this is for a online ecommerce store with reviews on products. Here's what I think:
All reviews data is stored in a table called 'reviews'
Field names: review_id, product_id, user_id, title, description, time_created, up_votes, down_votes, up_voters, down_voters
up_votes and down_votes contain the number of votes voting it up or down
up_voters and down_voters contain the user_id of the people who voted up or down in the format 1101.1102.1103 for users with user_id 1101, 1102 and 1103.
When a person clicks on the up vote button, the system will check if the current user's user_id matches anyone in up_voters. An explode function will turn 1101.1102.1103 into an array and in_array() will be used to check if the user has already voted.
Is there a better way to go about doing this?
That table will give you nightmares down the line. Just think of a hit product with 1K up_voters, your field will be 10K*4 characters long! Not just that, it will hinder your ability to make reports and study the data etc.
I don't know much about your needs but from what I can see in your table, I'd suggest the below.
review
user_id, product_id, type_of_vote, title, description, time_created
Use above table and use user_id, product_id as the key
OR
review
review_id, product_id, title, description, time_created
vote
review_id, user_id, type_of_vote
There are n number of ways to design tables for this. If it is an Operational Data Store(ODS) then you might want to normalize your design. If it's a warehouse then you may consider first table I mentioned above.
Related
I have a table with data relating to a user, and two important columns:
refer_count, which is updated when a new entry is made in the table with the referred_by column set to that users user_id, and referred_by which is the user_id of the of the user that referred them.
I want to select the users from the table that have the highest number of referrals after a certain date.
For example:
If there are 3 users, one of which referred the other 2 (lets say users 2 and 3), however user 2 was referred on the 2/12/14, whereas user 3 was referred on the 3/1/15.
If the cutoff is 1/12/14, then user 1 is returned with refer_count set to 2, but if the cutoff is after 2/12/14, then user 1 is returned with refer_count set to 1.
I've been thinking of how to do this, but I can't think of a way that would work. Is there a way?
This is via MySQL.
EDIT: I think I may need to provide for information.
The date registered (register_date) is used as the refer date. I need the refer_count to be updated with the number of users referred after the cutoff, however I need to get the actual user. This is for a 'top referrers' table. I can't figure out why I'm having so much trouble thinking of a way to do this.
SELECT user_id FROM usertable WHERE (referal_date BETWEEN '2014-12-2' AND CURDATE())ORDER BY refer_count DESC;
That's the rough idea.
You should look into normalizing your tables if you're keeping that all in the same table, though. It'd be better to keep referals in a seperate table.
Get the row with the maximum in refer_count with a Date condition for your referal_date such that it's after the certainDate:
SELECT user_id FROM table WHERE refer_count = (SELECT MAX(refer_count) FROM table) AND referal_date>certainDate;
Note that WHERE is before SELECT so it will not get the highest count first, but will filter with the date condition then get the highest count.
Edit: Updated query based on edited question.
We have to make a ballot system that makes users vote for various candidates on different positions. There's a login for voters. How do you store a vote of one voter and then get that vote added to the previous votes? The only possible way is to store every vote on a database right? But what would the structure of the database look like? And how do you count it?
edit:
The voting system doesnt only have one group of candidates to vote. It has mayor, vice-mayor, senator, etc. There are too many. that's why I'm confused. If only it was just a voting system of a president, it would be easier. So if I have a table for the voter, with a column of his/her voted candidate, it's not possible since the voter votes for many candidates.
A better way would be to have a different table to store Votes. And that table will have two attributes (VoterId, CandidateId)
And you can fetch the Vote Count if you are allowing multiple votes from this table..
But it would be better to make VoterId a Primary key in this table.. To avoid multiple voting
CandidateType: - (TypeId(PK), typeName, maxVotePerVoterForThisType)
Voter Table: - (voterId(PK), voterName, otherInfo)
Candidate Table: - (candidateId(PK), candidateName, constituency,
otherInfo, TypeId(FK))
Votes:- (voterId(PK, FK), TypeId(PK, FK), candidateId(FK))
*EDIT:- Schema edited with changed requirement in original post
*EDIT: - Added a field in CandidateType table to allow multiple votes.(E.g.: Now a voter can vote for 10 Senators, if maxVotePerVoter for this type is set to 10..)
You should e store each candidate in a table, positions in another table then make relations based on ID, the voting system is relatively simple:
database:
id, position_id, candidate_id, votes
then PHP
$query = "UPDATE `votes` SET `votes`=`votes`+1 WHERE `position_id`=1 AND candidate_id=1"; // adds 1 vote where position_id is 1 and candidate_id is 1
These 3 tables are required for your accounts (the voters) and candidates.
Account: Id (PK), Name, Password
Candidates: Id (PK), Name
Votes: AccountId (PK), CandidateId (PK)
Insert a row into votes when a vote is cast. This prevents duplicate voting due to the PK's.
I simple language i can say you are storing voting users in a table called users and you can use a field vaotecount (int) type initilize with zero and track their ip and vote for topic id on which they have voted for and when they vote you can check with IP and topic_id that they are not voting twice and if they passed you can increment the vaotecount field by one
and while you are counting for votes count the users with topic id for which you counting votes. Simple :D
From the explanation of problem, I can suggest you the following database structure:
tlbUserVote:
UserID(PK) | UserName | Vote | CandidateId(FK)
tlbCandidate:
CandidateId(PK) | CandidateName | TotalVotes
By this structure you can add the current votes with previous ones (by taking previous votes first and adding it to the current).
Total votes of the candidates will get updated, too.
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'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 have 3 tables
UserPosts(id, post, userfrom_id, userto_id, date)
GroupPosts(id, post, group_id, userfrom_id, userto_id, date)
CommunityPosts(id, post, community_id, user_id, date)
i want data from all theses 3 tables with related data like community name and image for community from community table (id, name, image)
similarly group's name and image from groups table and user, userfrom, userto's name and image from users table ordered by date
Now increasing the complexity a bit more UserPost has Many
UserComments(id, userpost_id, userid, commentm date) and
UserVotes(id, userpost_id,type, date) ps:type is like/unlike
Similarly GroupPosts have GroupComments ang GroupVotes and CommunityPosts has CommunityVotes and CommunityComments. i want this data too
Now increasing the complexity a bit more it needs to be ordered by comments too(no votes, phew). What mean is if a post is 1 month old but has the a comment that was put up 5 min AGO then i needs to be listed above a post posted 1 day ago with all comments greater than 5min.
Also in the result i would like to know if the particular record is a community record or a group record or a user record
This is sort off like a facebook homepage that shows all your, your groups and friends activity. I an using PHP(cakephp), Mysql. Hope i have given all the necessary data
Sounds like your are looking for JOIN.