Introduction
First of all, this is very basic what you wrote us. You should start specifiing those things and get more into details. For example for a diet plan you can think about the properties such plan could have. Properties are e.g. the length of the plan, the nutrition you need and maybe some sport-excercises. Just some samples. Then you may split up the nutrition in one table and so on. Now you can think about if you want to do all the database stuff on your own, or use a framework. Actually the whole database stuff seen in MySQL and so on is done on a webserver, because of security leaks on the client (decompiling, traffic reading, ...). If you want to save data on the local storage or in a local db (SQLite would be you choice) then you should also think about if you want to use an API for that (e.g. RoomAPI by Android Jetpack)
General thing
You should get your self a clear mind which architecture you want to use. You can store data on a webserver and transfer the data via web-interfaces e.g. REST with JSON or XML. You can also store data on the local device in a file or in a database (which is basically also a file with specific interface requirements). You have to decide and consider you require the exchange on multiple devices or just for one device on it's own.
Planning your structures
After you know which architecture you want to use, you can start planning. First of all I would suggest you to get an abstract view of your project. That means just writing down what you want to have and then start writing down the corresponding properties. For a diet-plan this may be the name of the plan, the length, required nutrition and so on... After that you may know, oh okay, I also need a table with the food and you will see (automatically) that there will be a connection. If you see the connection just draw a line connecting those. In an ideal situation you already know the relation of this connection (One to many, Many to one, Many to Many, One to One, see this stackoverflow article: Difference Between One-to-Many, Many-to-One and Many-to-Many?).
Implementing your structures
Anything I do is handcrafted
In the case you want to do all on your own you may use a gui tool for databases to design your database. You can also use commands to do that, what need much more effort. You can decide on your own and on your knowledge.
Pro for gui
- Easy to use
- Fast creation of the tables
Contra for gui
- May use some cryptic names for indexes and keys
- "May don't let you look behind the scenes"
I rely on APIs
You can also rely on APIs. That means often, that you can program the class according to your plan, then annotate it and the connections/relations would be managed by the api. Such abstraction-layer is Room for Android or Doctrine for PHP, those are just samples and there are much more.
Conclusion
How you get the data into the database and out of the database is your thing. You could rely on easy use of APIs or get your things done by yourself. It should be a little guide for you to understand database design.
P.S.: If someone has things to edit, do that! I would appreciate that!
Cheers Tarik.
