want to insert values to colum of one table to another

Question

want to insert values of one column to another

 

suppose i have two table

1)student(student_id(int),class_id,subject_name)

2)student_subjects(subject_id,subject_name,class_id)

i want at one shot subject_name will insert into column of 1)student(subject_name) from 2)student_subject(student_name) where class id=TextBox.Text

ie

1)student(student_id=textbox1.text,class_id=textbox2.text,subject_name=will come from (student_subject) table

that means

if student_subject table have 5 book it will short at one time along with student_id and class_id for five time