Can a lecturer force you to learn a specific programming syntax / language?
No, they can't. But they can make you fail the class.

Lecturers usually have free rein over the specifics of the material taught. Therefore they are free to choose any technology or dialect as long as it is within the area of the course.

Nobody can force you to study anything but if you want to pass his exam or the course by e.g. submitting lab problems, you have to play by their rules. 

They might not know any other dialect and therefore be only able to teach (and grade) Oracle SQL. Or they might consider it the best dialect, e.g., because of wide industry use.

Finally, although I would be annoyed by this as well, sometimes you have to suck it up and just pass the course. Lecturers that teach the same (obsolete) material for 20 years are unfortunately a reality in academia. At least you might learn what to avoid in the future.