Mysql

In Update we seen like updating an single row or multiple rows

UPDATE students
SET 
    name= 'rajesh'
WHERE
    rollno= 6;


can it be like conditional say chane pass into fail or fail into pass

To do this 

UPDATE 
        studnets 
SET grade = 
           CASE grade WHEN 
                             'Pass' THEN 'Fail' WHEN 'Fail' THEN 'Pass'
                              ELSE grade 
           END


Update with Join

UPDATE 
    employee
LEFT JOIN
    salary ON employee.performance = salary.performance 
SET 
    salary = salary + salary * 0.25
WHERE
    salary .performance >= 4;