SQL DATE extraction from a column

Question

I have a table 'schedule' and column 'travel_date'. travel_date is having 'a predefined date' in that.

I want to alter that column with '5days' more.

like

UPDATE Schedule SET travel_date=''+5days ;

I used UPDATE schedule SET travel_date = (travel_date+5); It worked how ?

Answer 1

In MySQL you can do that with

UPDATE  customer
SET     register_date = DATE_ADD(register_date, INTERVAL 5 DAY)