Fetching data from database to the table via dropdown

Hello everyone ! I am new to laravel world I searched so much for my problem but cannot find the appropriate solution ..... I have a dropdown of classes and when the user select any class and click the submit button then students related to that class will be displayed below in the table ..... In my database i have two tables one is for students where the student class id exist for every student and another table is for classes where class names are exist.. Now i can successfully get the classes to the dropdown but can't understand the logic that how i can get the students according to the selected class.. Thanks in advance