How to find the difference between 2 rows

Question

Table1

id no name value

001 grid1 rajan 200
001 grid2 rajan 300
002 grid1 mahesh 100
002 grid2 mahesh 200
003 grid1 jayan 200
003 grid2 jayan 50

I want to find the difference (GRID1 - GRID2) for each id

Expected output

id  name value

001 rajan -100
002 mahesh -100
003 jayan 150

How to make a query for the above condition

Need query help

Answer 1

select id, name, sum(case when no = 'grid1' then value else value*(-1) end)
from table1
group by id, name

see SQL FIDDLE Demo