I'm new to web design and I am making a niche social media site. I just want some general advice on the best way to design SQL database. I am using my sql and currently plan on having a profile table, that stores basic profile information (username, password, random other facts like location).
My question is can a cell serve as it's own separate table? I'm imagine each profile row will have a friends table inside of it that list all of the friends for that profile.
Is this the right way to go about designing? While not likely, i'd like a design good enough to scale in case I get thousands of users. Any advice would be greatly appreciated.
My question is can a cell serve as it's own separate table?
By "cell" I assume you mean a single value in a row. You cannot nest another table inside a row value. You could do something similar using an XML value, but more than likely what you are trying to accomplish is easily done using a foreign key in the friends table which references the primary key of the parent profile row. This known as normalization.
As for your other questions, those are too broad to be appropriate here. You should read through a basic tutorial/primer on database design. There are mountains of content someone could fill an answer with just to cover the basics of database design. "Database Normalization" and "database design best practices" are good starting Googles.
Related
I am new here as well as new in coding. I always get confused when it comes to database designing. Let me try to explain this.
If I need to create a functionality like this (Stackoverflow) website, More specific If I just want simple Question (posting, upvote, downvote) and Answer(posting, upvote, downvote) feature in my website I could follow two approaches.
First
create a table question in which I will save question.
create a table votes in which I will save votes(up and down).
To fetch a question will need to join these two table and get the question and there votes(up and down)
Second
Create a table question in which I will save question and votes count(tow more column to store count up and down votes)
Create a table votes in which I will save votes(up and down).
This time we can get the data from one tablw without join.
I always want to know which one I should use.
I know that in first approach we need to put more joins if we add more feature like (Share,View,Answer,etc).
And if i used second approach we need to take care of consistency and we also need to insert more times as in first approach.
I don't know someone who can answer this. That's why i am asking my question here.
Any help would be appreciated, Thanks.
You will learn a lot by looking at the Stack Exchange Data Explorer.
https://data.stackexchange.com/
In addition to seeing the schema and being able to type interactive queries, you can view, execute, and modify the excellent library of useful queries other people have contributed.
It's a wonderful way to learn from a real-world site.
I'm working on a project to make a digital form of this paper
this paper (can't post image)
and the data will displayed on a Web in a simple table view. There will be NO altering, deleting, updating. It's just displaying (via SELECT * of course) the data inputted.
The data will be inserted via android app and stored in a single table which has 30 columns in mysql.
and the question is, is it a good idea if i use a single table? because i think there will be no complex operation in the sql.
and the other question is, am i violating some rules for this method?
I need your opinion. thanks.
It's totally ok to use only one table, if that suits your needs. What you can do to make the database a little bit 'smarter' is add new tables for attributes in your paper that will be repeated. So, for example, the Soil Type could be another table where there are two columns, ID and Description, and you will use it as a foreign key in each record in the main table. You need this if you want your database to be in 3NF.
To sum up, yes you can have one table if that's all you need. However, adding more tables might help save some space and make your database more flexible. It's up to you to decide! :)
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About the Program
Excuse the vague title, but I'm rather new to mySQL and databases. I'm a developer in VB.NET and need to create a program that connects to a database. The program is a guide for a game, and part of the program gives you directions to your next objective when you select a mission. For example, from the application (made in WinForms), you select a "mission" from a combo-box control, and a Textbox will populate according to the objectives in the database. A further example could be displayed as this:
You Select "The First Misson" from the Combo-Box control.
The Textbox Control now contains a numerical list of objectives in order, like so:
Locate John.
John asks you to find a weapon
Give the weapon to John
Help John fight off the monster
John asks you to heal him with a potion
Help John reach the portal at the end of the tunnel
Speak to John about your rewards
Now, the question is how may I display a list like the one above using a database? I was reading up on normalization; however, I still do not see how this may be done.
This is an example of the application (just a mock up, but very similar):
Now say the user selected a misson from the Combo-box located at the top of the application. The application would populate like so:
Ideas via Normalization
I understand I could create two seperate tables containing data relating to the misson. For example, I might be able to create a table called "Stages", and a table called "Missons", but I see this as inefficient, not to mention populating the database itself would take ages. I quickly found that you could not (obviously) store a list in a single cell. So being just a programmer, and not someone who works with databases, I this is very frustrating.
(If it may help, I can also alter the application in which is retrieving data from the database to allow a list to be displayed a different way.)
The Overall Issue
There may be "work-arounds" to address this problem, but I don't know what to do. I do not understand how you could display such data using a database. I understand how you connect to the database and retrieve data using queries, just not with a list. Also, an elaborate answer would be much appreciated for a newbie at this like me.
From what I read, you seem to be primarily stuck up on database relationships. No worries! When you want a "list" in a database, this means you are looking for a one-to-many relationship, or a many-to-many relationship. Here is a brief tutorial that explains the differences between these types of relationships.
One of the first steps in database design is to define your entities (i.e. your tables.) In general, your entities will typically be major nouns from your business problem. In this case, you clearly have the following entities (tables): Mission and Objective. The only other data present on your form is a textbox for mission location and a textbox for mission requirements. Both of these fields can be single properties of the Mission table.
The next step is to define your entity relationships. You might define your relationships as follows:
A Mission has one-to-many Objectives
An Objective belongs to one Mission
Finally, lets list out our known properties:
A Mission has a name (text)
A Mission has one location (text)
A Mission has one requirement (text)
Now we can create a basic database schema. So. What would this look like?
Each table has it's own primary key, denoted by the key image in the picture above. The primary key is a unique identifier for a row of data and is usually represented by an integer. The Objective table also has a foreign key, the missionID field. This is how the one-to-many relationship is defined between these tables.
This way, if we create a Mission with missionID 1, we can assign this missionID to many Objectives. Just like a list, but in the syntax of a relational database. See the images below:
In order to retrieve information about both entities at once, you might use a JOIN query. Hope this helps!
You probably should read up on entities and relationships.
Entities are database parlance for things like a game, a mission, a requirement, and a player (a person).
Relationships are database parlance for statements like
each game has one or more missions in it
each mission has one or more requirements in it, displayed in order
zero or more players can be playing each game.
Each table in your rdms is a collection of instances of a particular entity. So, you'll have a requirement table, for example, that will record the following information for each requirement, each in its own row of the table, for example
game_id the game for which this is a requirement
mission_id the mission for which this is a requirement
requirement_ordinal 1,2,3,4 etc for which requirement in sequence this one is.
description the text describing the requirement: "Speak to John about normalizing your rewards."
You may declare that a particular combination of the first three items uniquely identifies each requirement, which is to say that (game_id,mission_id,requirement_ordinal) is the primary key for the requirement table.
Desktop apps like MySQL Developer and MS Access have graphic design tools that let you draw this stuff in a charts. Here's a writeup. http://docs.oracle.com/cd/A87860_01/doc/java.817/a81358/05_dev1.htm This business of entity-relationship modeling can get very elaborate and abstruse, so be careful not to dive in too deep.
Working this all out is what database design is about. I can't design this whole thing for you, but I can offer you some jargon and a conceptual framework to help you figure out how to search for it.
I'm creating a small community using the Symfony2 Framework and backboneJS.
When I took a look at the database today I realized that it might be wrong to store all images using this schema.
ImageTable
Id
Title
Owner
Description
Url
So when a user logs in and wants to have a look at his own images, I just loop through all images where owner == currentuser.
Is this a bad practice?
The more owners I have the longer the query its going to take, right?
I'm asking since it might take a week to restructure the whole website database and I don't want to fix what might not be broken.
I know a solution might be to set a manytomany relationship between the current user table and an own image table, but is it worth the effort?
As far as I can see, this is as normalized as it gets for your scenario. A many to many relationship is not what you are looking for, since a user may have multiple images, but an image can't have multiple owners (or can they?).
So if the Owner is a foreign key for the table user you are good.
this is a follow-up question on my previous one.We junior year students are doing website development for the univeristy as volunteering work.We are using PHP+MySQL technique.
Now I am mainly responsible for the database development using MySQL,but I am a MySQL designer.I am now asking for some hints on writing my first table,to get my hands on it,then I could work well with other tables.
The quesiton is like this,the first thing our website is going to do is to present a Survey to the user to collect their preference on when they want to use the bus service.
and this is where I am going to start my database development.
The User Requirement Document specifies that for the survey,there should be
Customer side:
Survery will be available to customers,with a set of predefined questions and answers and should be easy to fill out
Business side:
Survery info. will be stored,outputed and displayable for analysis.
It doesnt sound too much work,and I dont need to care about any PHP thing,but I am just confused on :should I just creat a single table called " Survery",or two tables "Survey_business" and "Survey_Customer",and how can the database store the info.?
I would be grateful if you guys could give me some help so I can work along,because the first step is always the hardest and most important.
Thanks.
I would use multiple tables. One for the surveys themselves, and another for the questions. Maybe one more for the answer options, if you want to go with multiple-choice questions. Another table for the answers with a record per question per answerer. The complexity escalates as you consider multiple types of answers (choice, fill-in-the-blank single-line, free-form multiline, etc.) and display options (radio button, dropdown list, textbox, yada yada), but for a simple multiple-choice example with a single rendering type, this would work, I think.
Something like:
-- Survey info such as title, publish dates, etc.
create table Surveys
(
survey_id number,
survey_title varchar2(200)
)
-- one record per question, associated with the parent survey
create table Questions
(
question_id number,
survey_id number,
question varchar2(200)
)
-- one record per multiple-choice option in a question
create table Choices
(
choice_id number,
question_id number,
choice varchar2(200)
)
-- one record per question per answerer to keep track of who
-- answered each question
create table Answers
(
answer_id number,
answerer_id number,
choice_id number
)
Then use application code to:
Insert new surveys and questions.
Populate answers as people take the surveys.
Report on the results after the survey is in progress.
You, as the database developer, could work with the web app developer to design the queries that would both populate and retrieve the appropriate data for each task.
only 1 table, you'll change only the way you use the table for each ocasion
customers side insert data into the table
business side read the data and results from the same table
Survey.Customer sounds like a storage function, while Survey.Business sounds like a retrieval function.
The only tables you need are for storage. The retrieval operations will take place using queries and reports of the existing storage tables, so you don't need additional tables for those.
Use a single table only. If you were to use two tables, then anytime you make a change you would in effect have to do everything twice. That's a big pain for maintenance for you and anyone else who comes in to do it in the future.
most of the advice/answers so far are applicable but make certain (unstated!) assumptions about your domain
try to make a logical model of the entities and attributes that are required to capture the requirements, examine the relationships, consider how the data will be used on both sides of the process, and then design the tables. Talk to the users, talk to the people that will be running the reports, talk to whoever is designing the user interface (screens and reports) to get the complete picture.
pay close attention the the reporting requirements, as they often imply additional attributes and entities not extant in the data-entry schema
i think 2 tables needed:
a survey table for storing questions and choices for answer. each survey will be stored in one row with a unique survey id
other table is for storing answers. i think its better to store each customers answer in one row with a survey id and a customer id if necessary.
then you can compute results and store them in a surveyResults view.
Is the data you're presenting as the questions and answers going to be dynamic? Is this a long-term project that's going to have questions swapped in and out? If so, you'll probably want to have the questions and answers in your database as well.
The way I'd do it would be to define your entities and figure out how to design your tables so relationships are straightforward. Sounds to me like you have three entities:
Question
Answer
Completed Survey
Just a sample elaboration of what Steven and Chris has mentioned above.
There are gonna be multiple tables, if there are gonna be multiple surveys, and each survey has a different set of questions, and if same user can take multiple surveys.
Customer Table with CustID as the primary key
Questions Table with a Question ID as the primary key. If a question cannot belong to more than one survey (a N:1 relationship), then can also have Survey ID (of table Survey table mentioned in point 3) as one of the values in the table.
But if a Survey to Question relationship is N:M, then
(SurveryID, QuestionID) would become a composite key for the SurveyTable, else it would just have the SurveyID with the high level details of the survey like description.
UserSurvey table which would contain (USerID, SurveryID, QuestionID, AnswerGiven)
[Note: if same user can take the same survey again and again, either the old survey has to be updated or the repeat attempts have to stored as another rows with some serial number)