Whats your website stack?
How do you host it?
Share the link to your site or an example log so that we can check out what kind of data needs storing.
There are several ways to store some data either on the users end or on the backend, with different pros and cons. But which one you should pick is highly dependent on the stack and the details of your needs.
Depends on the career path. Some need only the very basics - for example in frontend development, you’ll mostly use % and basic +/-.
tbh. Most of the useful programming related knowledge you’ll learn at yoyr first job, not at uni.
The curriculum sometimes will force you to learn something unrelated to your career and it has multiple purposes:
People learn the fastest in the topic where they already know a lot. And the slowest where they know very little.
Learning stuff outaide of your comfort zone literally works out your brain. You learn to learn. And your thinking becomes more flexible.
You should not become somebody who is only good at one narrow singular task and a complete idiot at anything else.
You never know if it becomes useful later in life. So I suggest still trying to do your best at any topic. And studying more for the exams where you are not as proficient.
As to which career path to go for:
Don’t be afraid to change midway, but make sure that you enjoy it. If you enjoy compsci, keep at it. (Or if you have student loan, put some more thought into the cost of switching).