How to divide two values from the different row in SQL

Question

hi everybody,

 

i have a this formula  

Quote change = (current month / previous month) * 100

 

my data stored in sql  table like that ;;

 

id --- date -                         data

1       2015/01/01             10

2       2015/02/01             15

3       2015/03/01             20

4       2015/04/01             15

.

.

.

. 

10   2015/10/01             85

 

how can i implement this function on sql  

 for example current month is 2015/02/01

Quote change = (current month data / previous month data ) * 100

 Quote change =( 15/10)*100

 

then if now is   2015/01/01. because no any data before  2015/01/01 this i need to show 0 or - 

 

anybody can i help me  ?