I've been using this site as a great resource since I started at school - but I've never had a problem this specific before and I was hoping for a bit of help. I was never the best when it came to figuring out database structures, and I've been tasked with creating a PHP/MySQL test engine with some rather specific specifications.
So you can better understand what I'm going for here - I am trying to take into account the following:
Administrator and student login are required, and provide different levels of access.
An administrator should be able to build one or more tests and assign it to one or more students.
For each question an administrator builds within a test, the administrator should be able to assign a point value.
A test should be able to present one or more questions.
Your application should support three basic questions types: true/false, multiple choice and fill in the blank.
Final results will display an overall score, as well as a student’s response to each question.
A student should be able to see final results for only test they have access to.
An administrator should see results for tests from multiple students.
Students are not allowed not retake the same test.
Mostly, I am trying to deal with the basic structure. I had five tables at the start, I condensed the Question/Answer section into one table - and excuse my poor attempt at switching around the relationships here, because I've had them 20 different ways it feels:
Am I on the right track? Any suggestions?
A good rule of thumb with database design in N-1. For all tables that have relationships, you should have N-1 relationships (where N is the number of tables). Tables with circular references are a no-no. Putting as the security components and just looking at test/questsion/answers, you want a design that has Some basic objects:
Admin (or teacher) table
Test table
Student Table
Question Table
You didn't mention it in your question, but if you want each test to be associated with a class that the teacher teaches, you will need that as well. With those four, or five, tables you should be able to create your relationships. Hint: Most of these relationships are many-to-many and, as such, will need an XRef table to resolve this. Post back what you do with this and we can look at what's next.
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i am struggling with setting up my database and eloquent relationships in a certain scenario.
This certain part of my application will be handling online orders.
basically i want an order to consist of multiple configured items.
i want configured items to consist of a base item (ex. a cheesburger) and also of toppings.
i have gone through several scenarios, but I am trying to make this as simple as possible. here is the quick and dirty story of what I have now.
I want a configured item to consist of three things. 1. the order id of the order it is associated with. 2. the menu item that it relates to (ex. cheeseburger, hotdog ) 3. and the toppings.
I am considering two tables that are full of relatively static information about the menu items and the toppings to be referenced from the configured item table.
I had originally considered creating a new menu item on every configured item, but I like the idea of just being able to look up items/toppings and applying them to a configured item. Im sorry if this is unclear. I am three days into this and my brain is absolutely in pain by now.
here are the relationships i am considering.
configured_item: belongsTo Order; hasOne menu_Item;
Menu_item: belongsToMany configured_item; hasMany toppings;
Toppings: belongsToMany configured_item;
I guess in a way my configured item table is a pivot table of sorts, but then it will need to be referenced by an order as well.
i know questions have been asked about three way relationships, but I cant find any info on tables that are relatively static like i am trying to use.
I finally caved and used two pivot tables. it all works, but i cannot help but feel there is a better way to handle this. It seems a lot of people have similar issues and there is no clear cut solution.
The project that I am working on requires a sort of sharing functionality meaning that when a person creates an exercise they can choose to share that exercise with another person and append a certain permission to that exercise (i.e read, write, or execute).
I have three tables(all of which have models): users, exercises, and permissions. In the middle I have an exercise_permission_user table that only has three columns: exercise_id, permission_id, and user_id all of which are foreign keys that point back to their respective tables.
The problem comes with establishing a three way many to many relationship among these tables in Laravel 5. More specifically, when a person shares an exercise, I need to input the id's of the exercise being shared, the user it is being shared with, and the permission that is being appended into the exercise_permission_user table. I then need to be able to query the user_id of this table and see all exercises that are being shared with a certain user. If the user Mike has an ID of 3, then I would like to query the middle table for that ID and find the exercise he has access to as well as the permission that he is being granted.
I am still in the learning process when it comes to eloquent so any help would be greatly appreciated. I am not necessarily looking for someone to build this for me, just some help that will give me the information necessary to do it on my own. Thanks to all that help!
I've struggled with this issue a couple of times. As far as I could research, I didn't find a Laravel native way of coding this kind of three way many to many relationship. What I generally do is to create a model for the pivot table. So, a SharedExercise model (or the name you want to use) with a protected $table property set as 'exercises_permission_user'. Inside that model you set the relationships with user, exercises and permissions. Then, you can write:
$sharedExercises = SharedExercise::where('user_id', $userId)->get();
Pay attention to the table and model naming. I usually name tables using laravel's conventions, but when I have this 3 way many to many, I try to find a more describing name than the convention. So, for example instead of exercises_permission_user and ExercisePermissionUser model, maybe shared_exercises and SharedExercise names are better.
Note that this isn't THE way to do it. It's how I do it as a result of not finding a convention in the documentation.
Currently working on a new project, where different components can be entered and connected to eachother. The trick is that the amount of components and the data in a component can be anything, making it hard to find some sort of database-logic in it when it comes to table-setup and keys.
For example I have the following components:
cars
name: audi, color: red, horsepower: 500
bicycle
name: mybike, color: blue, lights: front and back
Etcetera. These components have some types in common, like name and color, but some different types, like horsepower on a car and lights on a bike.
These components can really be anything, but I need a way to link these together somehow in a database-structure that still makes sense.
Ive figured I could define a component-table that simply feeds an ID, with a seperate component-type table next to it per component. However that would require a different table everytime someone comes up with a new component (which again could be anything at any time).
I really do need to be able to structure these and link them together somehow, for example link that car to that bike.
Im running into a bit of a wall in my head thinking about this and hope someone can help me figure out how to do this in mysql.
The open ended database model that fits this use case is the Entity Attribute Value (EAV) model http://en.wikipedia.org/wiki/Entity%E2%80%93attribute%E2%80%93value_model. The problems that you encounter with this model are performance and complexity of queries. Now some DBs can assist you with pivot functions that will turn rows into column, but MySQL is not one of them. So if you go with this model then go with postgres as it has crosstab which will pivot the single row attributes of an entity into columns.
While reading, please keep in consideration I'm still learning Symfony2, as I'm new to it. I'm a bit stuck into this so I haven't done anything yet - in fact, I come to you exactly to get myself lead to the right place.
I have, as my requirements, to enter student data into a form. The issue is that most of the data is already split into several classes with indirect relationships. A Person has one InformationContainer, which in turn has several Roles and InformationUnits (some information units are mandatory only when certain roles are added). In turn, Student is a role and it has several StudentAntecedents (as it can vary yearly), which has a Representative (ManyToOne), which is a Role. Also, InformationUnits can hold several information such as birthplace, ethnicity, etc.
As you can see, this has several classes in it. But I must add Person information, InformationUnit information and StudentAntecedent information (and not all of them) in one form. I'm aware I could just go ahead and use embedded forms but I have the feeling it could break (Person does not associate directly to InformationUnits, for instance). How do I do this?
Thank you beforehand.
I am lost on how to best approach the site search component. I have a user content site similar to yelp. People can search for local places, local events, local photos, members, etc. So if i enter "Tom" in the search box I expect the search to return results from all user objects that match with Tom. Now the word Tom can be anywhere, like a restaurant name or in the description of the restaurant or in the review, or in someone's comment, etc.
So if i design this purely using normalized sql I will need to join about 15 object tables to scan all the different user objects + scan multiple colunms in each table to search all the fields/colunms. Now I dont know if this is how it is done normally or is there a better way? I have seen stuff like Solr/Apache/Elasticsearch but I am not sure how these fit in to myusecase and even if i use these I assume i still need to scan all the 15 tables + 30-40 colunms correct? My platform is php/mysql. Also any coding / component architecture / DB design practice to follow for this? A friend said i should combine all objects into 1 table but that wont work as you cant combine photos, videos, comments, pages, profiles, etc into 1 table so I am lost on how to implement this.
Probably your friend meant combining all the searchable fields into one table.
The basic idea would be to create a table that acts as the index. One column is indexable and stores words, whereas the other column contains a list of references to objects that contain that word in one of those fields (for example, an object may be a picture, and its searchable fields might be title and comments).
The list of references can be stored in many ways, so you could for example have string of variable length, say a BLOB, and in it store a JSON-encoded array of the ids & types of objects, so that you could easily find them afterwards by doing a search for that id in the table corresponding to the type of object).
Of course, on any addition / removal / modification of indexable data, you should update your index accordingly (but you can use lazy update techniques that eventually update the index in the background - that is because most people expect indexes to be accurate within maybe a few minutes to the current state of the data. One implementation of such an index is Apache Cassandra, but I wouldn't use it for small-scale projects, where you don't need distributed databases and such).