I have a sql table where i'll store all my employee details. employees are of different categories like "A", "B", "C" and "D". now i want to a single update query which updates the salaries of employees. "A" and "B" category employee's salary has to be increased by 20%, for "C" it is 15% and for "D" it is 12%. i want to make all these in a single update statement. how can i do that.