How to assign grade student mark wise in SQL

Description : In this post how to apply a grade in student table using case when condition

Step 1 : Write below query from update rank in student table

UPDATE tblStudent SET tblStudent.Grade = CASE
    WHEN Mark BETWEEN 0 AND 100 THEN 'C'
    WHEN Mark BETWEEN 101 AND 120 THEN 'B'
    WHEN Mark BETWEEN 121 AND 150 THEN 'A'
    ELSE 'A+' END
FROM tblStudent AS St

Step 2 : Select student table for check result

SELECT * FROM tblstudent

Result is

Student1        100    C
Student2        120    B
Student3        100    C
Student4    150    A
Student5    150    A
Student6    160    A+
Student7    135    A
Student8    129    A
Student9    155    A+