cloudnote_server/src/main/java/com/bupt/note/Repository/UserRepository.java

package com.bupt.note.Repository;

import com.bupt.note.Model.User;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
    boolean existsByUserName(String username);
    User findByUserName(String userName);
}