Neither sentence is correct.
You might say:
- 저는 학교의 학생이에요 (의: possessive. I am a student of a school)
- 저는 학교에 있는 학생이에요 (에: locative. -에 있다: am in someplace. "I am a student in school.")
- 저는 학교(에/를) 다니는 학생이에요 (다니다: go to, attend. I am a student who attends school.)
All three are grammatically correct, but the last one sounds the most natural.