Just got a question here about a database table. If the table only has a primary key (identity) and 1 column of useful data, is it okay to be its own table or should it be in the parent table as just the data?
The table is storing Security Questions that the user will set up with they make their account and be used to reset password in the event they want to change password or forgot the password. I have the ID of the question, and the question string in this table.
The reason I have it in its own table is that the same question could be used for many users so why store the question many times in the parent table. Thats my thinking, just wanted a few others' opinions on this.
EDIT: The Security Questions are going to be input by my team, not the user themselves. The user will pick one of the questions to use.
I would suggest this sample design using bridge table:
You can have multiple questions for a user as well as their answers unique. Also, the questions can be same for multiple users.
You must always try to prevent duplicates, that's why your solution is the best.
it will also keep your database smaller. A foreign key with int value is smaller than a string.
Related
I've already designed a website which uses an SQLite database. Instead of using one large table, I've designed it so that when a user signs up, a individual table is created for them. Each user will possibly use several hundreds of records. I done this because I thought it would be easier to structure and access.
I found on other questions on this site that one table is better than using many tables for each user.
Would it be worth redesigning my site so that instead of having many tables, there would be one large table? The current method of mine seems to work well though it is still in development so I'm not sure how well it would stack up in a real environment.
The question is: Would changing the code so that there is one large database instead of many individual ones be worth it in terms of performance, efficiency, organisation and space?
SQLite: Creating a user's table.
CREATE TABLE " + name + " (id INTEGER PRIMARY KEY, subject TEXT, topic TEXT, questionNumber INTEGER, question TEXT, answer TEXT, color TEXT)
SQLite: Adding an account to the accounts table.
"INSERT INTO accounts (name, email, password, activated) VALUES (?,?,?,?)", (name, email, password, activated,)
Please note that I'm using python with Flask if it makes any difference.
EDIT
I am also aware that there are questions like this already, however none state whether the advantages or disadvantages will be worth it.
In an object oriented language, would you make a class for every user? Or would you have an instance of a class for each user?
Having one table per user is a really bad design.
You can't search messages based on any field that isn't the username. With your current solution, how would you find all messages for a certain questionNumber?
You can't join with the messages tables. You have to make two queries, one to find the table name and one to actually query the table, which requires two round-trips to the database server.
Each user now has their own table schema. On an upgrade, you have to apply your schema migration to every messages table, and God help you if some of the tables are inconsistent with the rest.
It's effectively impossible to have foreign keys pointing to your messages table. You can't specify the table that the foreign key column points to, because it won't be the same.
You can have name conflicts with your current setup. What if someone registers with the username accounts? Admittedly, this is easy to fix by adding a user_ prefix, but still something to keep in mind.
SQL injection vulnerabilities. What if I register a user named lol; DROP TABLE accounts; --? Query parameters, the primary way of preventing such attacks, don't work on table names.
I could go on.
Please merge all of the tables, and read up on database normalization.
Im building a friendship site where I try and match users who share similar interests.
I have 25 questions with defined answers(drop down answers) that the user must fill out.
Im using an entity–attribute–value model to store the users id the question id the answered id the user selects.
I then use the count function to see which users have the most matches to my profile.
Current Table Structure
Question Table
Answer Table
Question_Answer_User Table
The problem im running into is I have two question and im not sure where the best place to store them is.
The question is what is your country?
The question is what is your State?
Im not sure if I should store them with the other 25 questions or if i should store them in a three separate tables as seen below.
country table
state table
user_country_state Table
There are going to be alot of answer entries for these 2 questions. For example there are 25 countries the user can answer and a total of 900 states / provinces the user can answer from.
I want to be able to consider the users location as similarity to count but im not sure what the best approach to incorporate this is?
I think the selected country and state should live in the user table, along with the other necessary user information such as name and email address. I don't think it belongs in the Answers table, but it would work there.
For the list of options for the user to select from when setting up his account, storing them in your pre-defined Q and A tables are as good a place as any. It depends, I guess, on how your data and functionality is broken apart so that you aren't crossing responsibility boundaries for the Q&A table storing survey-type answers as well as user-setup answers.
I'm working on some asp.net application, I got stuck in following business.
Suppose we have a person, and he can open both types of accounts and each account has some transaction history. Person table has some primary key say PPK, and customer table has some PK as PIN.
My question is how to solve/present this scenario in database, relation of person table to customer table is 1:2 as no person can have more than two account. and what about that transaction table? that holds all transaction history for some specific account? shall I make two transaction table (which is really a bad idea because as account type exceeds transaction tables exceeds).
Can I build their relation as 1:* (then I may need another table for that. it holds Fk of both table. )
or Can make pin as unique key and always open database for like checking limit of accounts (i.e. two).
I really need some suggestions.
All suggestions are welcome.
Thanks!
P.S: If you dont understand the question please ask me before reporting it away please!
You can either do something like this:
Or something like this:
The first model allows adding more accounts by just changing the CHECK (in case requirements change in the future), while the second would require adding another column in such case.
NOTE: The above assumes both account types are structurally identical, so they "fit" into same table. If that's not the case, you can use inheritance.
Ok you have a person table and an account table with a foreign key relationship between the two which is 1 person to many accounts. Then you have a transaction table that is related to the account id in the account table which is also 1 account to many transacations.
Now to enforce the limit of only two accounts being allowed, for that you want a trigger that checks when a record is being inserted or updated to amek sure the person currently has no more than one other record.
I am trying to implement a system on my website similar to that of Facebook's "Like" feature. Where users can click a button which counter++'s. However, I have run into a problem in terms of efficiently storing data into my DB.
Each story has it's own row in the stories table in my DB with the columns like and users_like.
I want each person to only be able to like the story once. Therefore I need to somehow store data that shows that the user has, in fact, like++'d the post.
All I could thing of was to have a column named users_like and then add each user, followed by a comma, to the column using CONCAT and then using the php function to explode the data.
However, this method, as far as I know, is in the opposite direction of database normalization.
What is the best way to do this and I understand "best" is subjective.
I cannot add a liked flag to the user table because there will be a vast number of stories the person could 'like.'
Thanks
You need a many to many table in your database that will store a foreign key to the stories table and a foreign key to the user table. You put a constraint on this table saying that the story fk - user fk combo must be unique.
You now don't even have to have a like column, you just count the number of rows in the many to many table corresponding to your story.
This question is based on my plan at the thread.
The following figure shows relations in my database
alt text http://files.getdropbox.com/u/175564/relation-figure.png
I have two "help-tables": questions-subjects and check-moderator. I use the former because one question can have many subjects, while the later because more than one moderator can check a question.
I left out the 1-to-1 number out at the arrows.
The dotted arrow between the tables question and moderator-check indicates that there may be questions which moderators do not check.
This is my first database-project so there are mistakes in the tables.
What would you improve in the table?
User, UserInfo, Moderator and Password are redundant tables that offer no benefit.
They only express 1-1 relationships with User, so there is no need to normalize them into seperate tables:
Make one table:
UserId
Name
Email
PasswordMd5
IsModerator
Reply to FlySwat's answer
I changed my table to the following based on your answer.
alt text http://files.getdropbox.com/u/175564/table-problem-3.png