C# Database: combobox value base on another combobox. How?

Question

I have an application that display some info from access 2016 database. - Form2 will display data from studentInfo table so Form2 will contain studentIDTextBox, studentNameComboBox, classComboBox, levelComboBox, studentDateDateTimePicker, nationalityComboBox, cityComboBox, provinceComboBox, blockTextBox...etc

 

levelComboBox:

• SelectedValue: studentInfoBindingSource - Level
• DataSource: studentLevelBindingSource
• DisplayMember: Level
• ValueMember: LevelID

classComboBox:

• SelectedValue: studentInfoBindingSource - Class
• DataSource: studentClassBindingSource
• DisplayMember: Class
• ValueMember: ClassID

 

Now my question is: Without effect the info has been display i want if i add a new item ( record ) to the database and when i choice a specific Level from levelComboBox it will change a list of classes within the selected Level in classComboBox and vice versa. How i can do that ?

I try to do that by using the code below but it is not good:

private void provinceComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
   var cityQuary =
      from displayCity in student1516DataSet.city
      where displayCity.ProvinceName == provinceComboBox.Text
      select displayCity;

   cityComboBox.DataSource = cityQuary.AsDataView();
}