Java spring extract student from specific course (SQL)

See more:

Java

MySQL

Ubuntu

springboot

Hello.I have a java project running in the web (localhost).
Something like this[^]

So,I have some courses from a sql script.
Also,I have a html file that contains 3 buttons such as (Edit,Remove,Show Students).
So, I want to extract all the students that are enrolled in the corresponding lesson.The function I wrote is:
this one[^]


StudentService.java file photo:here[^]



Sorry for using photos instead of code.
Any help would be appreciated.Thanks.

What I have tried:

SQL script:
1st photo[^]
2nd photo[^]
3rd photo[^]