i want to add 2 days to column based on other column i use this table :

Company   Type Joinning Date  Starting day
1         1    19/01/2019     
2         0    19/01/2019       
3         0    19/01/2019       
4         1    20/01/2019     
5         0    20/01/2019
6         1    21/01/2019     

i want to add 2 DAYS in column Starting day which is Joining day 2 days if the company have type 1 how can i do it ?

What i've tried ?