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Inserting and updating NULLs
6. UPDATE with NULL in SET
Conditions in UPDATE and DELETE
Using values from another column
Inserting data from a query


Fantastic! You already know how to insert data with NULLs. You can also use NULL in UPDATE statements.

Suppose the teacher made a mistake. Tom Muller took the written exam, but the teacher hasn't checked this exam (exam ID of 17). Nevertheless, Tom has the score of the written exam (written_exam_score) and the date (written_score_date), but he shouldn't. In this case, the only known value is the actual date of the written exam; you must move the other two values. How would you do this?

It's simple! Look at the command below:

UPDATE exam 
  written_exam_score = NULL, 
  written_score_date = NULL
WHERE id = 17;

After SET, we used two comma-separated column names to update written_exam_score and written_score_date. Each column was assigned NULL. In the WHERE condition, we update only the exam with id = 17. In this way, we correct our mistake.


In the database, the teacher stores the student name Laura Donna Ross (id = 10). However, Laura doesn't have a middle name; Donna is a mistake. Correct this mistake by updating the data.