Since it is not a "what database is better" question at all, but rather a "how can I solve a problem" question (and a very common problem), I think the question is valid.
- How is a .NET application, using MySQL still a good option or is SQL Server more secure?
Both MySql and SQL Server can serve your purpose well. I recommend SQL Server only because it is easier to integrate with .NET applications. If you were to work with PHP or Ruby, I would recommend MySql.
SQL Server has an Express edition that is free. It has some limitations like using at most a certain amount of memory and processor resources, but for your case, I believe that would be no problem. If SQL Server Express limitations are a problem, then you will not be able to solve your company's problems with only one application of the type you intend to do;)
Firstly, I chose to set up a local server in the office, and leave the application on the notebook, leaving the desktop unique to being the database.
You can also pay $ 5 a month to host a database in any Internet hole (sorry for the expression, but it's to emphasize the banality of the thing). That way you will not lose the entire database when the machine breaks.
However, somebody may see this as a "waste of resources" (leaving the computer stopped and turned on without "using").
The next time someone raises this argument, ask the person how much it costs to keep a computer connected during work hours. Look at the impact on the energy bill and be surprised how cheap it is.
Would it be safe to leave it productive (with one person using it to read emails, access the internet, etc.) and at the same time save application data? Or should I isolate it to just save the data?
You'll just replace Excel, and do nothing as complicated as analyzing genetic material or weather patterns, right? You can run quietly on a regular machine while the
desk spends the day on Facebook works on your computer. As long as it's really an ordinary machine, not a wagon (for example, something with two gigabytes of RAM or less, by current standards).
I also thought about using a VPS to save the data, making it possible to use the program in other places (which can be useful). However, I would have to protect the database against attacks that would not be necessary if the database was local (if it were a local someone could steal the computer with the data, but that's another story). Is it more feasible to invest a little in leaving the data in the cloud or being safer and leaving it locally?
Using a good authentication scheme and saving the salty password hash should be sufficient to protect all the industrial secrets of the military research done for DARPA that your company stores in Excel;)
I may be getting too much of an exaggeration. It would also be possible to save the data along with the application, rather than configuring a server just for that. However, I find this somewhat wrong and unsafe, but I may be wrong.
If you meant that you can run the application on the same machine as the bank, that's fine. If you meant to save the information in an application's own format and dismiss the bank, no, you're not wrong.
Editing: Excel has ways to allow group work on the same worksheet. All changes are merged in real time. If you want to keep things simple, maybe this will help. But a database allows information to be better organized and queried more quickly, so I recommend that you continue to search for a database solution.