let's say i want to execute following mysql and few records already exists in table and there may be more than one record which already exists.
if this record `(21,'Helen','a')` and `(21,'Hui Ling','b')` already exists in table and i want to execute insert and update with where condition like.. `where name = "Helen" and grade="a"` then what should be my update query part. 

```
INSERT INTO students (points,name,grade)
    VALUES
    (21,'Helen','b'),
    (21,'Helen','c' ),
    (21,'Samia','a'),
    (21,'Hui Ling','b'),
    (21,'Yumie','a'),
    (21,'Helen','a')
ON DUPLICATE KEY UPDATE
    grade = VALUES('a'),

```