I am using jpa. I establish a many to many relationship on Course and Student. So I have a bridge table CourseStudent.

The code in Course,java
@Entity
@Table(name = "COURSE")
public class Course implements Serializable {
@ManyToMany(fetch = FetchType.EAGER)
@JoinTable( //
name = "COURSESTUDENT", //
joinColumns = { @JoinColumn(name = "COURSE_FK", nullable = false, updatable = false) }, //
inverseJoinColumns = { @JoinColumn(name = "STUDENT_FK", nullable = false, updatable = false) })
public Set<Student> getStudents() {
return students;
}

public void setStudents(Set<Student> students) {
this.students = students;
}
@Transient
public void addStudent(Student student) {
Set<Student> students = getStudents();
if(students == null) {
students = new HashSet<Student>(0);
setStudents(students);
}
students.add(student);
}

@Transient
public void removeStudent(Student student) {
Set<Student> students = getStudents();
if(students != null) {
students.remove(student);
}
}
Code in Student.java
@Entity
@Table(name = "STUDENT")
public class Student implements Serializable {
@ManyToMany(fetch = FetchType.EAGER, mappedBy = "students")
public Set<Course> getCourses() {
return courses;
}

public void setCourses(Set<Course> courses) {
this.courses = courses;
}

The problem is when I want to remove one student record from the student collection of the course, no corresponding record got removed. the code is looks like:
course.removeStudent(student);

Any help would be appreciated. Thank you so much.
Note: insert and update is fine.