Need Query for Connected numbers

I have a simple scenario.
there is a chain of numbers connected together,
say 1-2-3-4-5.
This chain is present in a table(number,grp), which represent each connection between two numbers as two different records, having same grp id.
for connection 1-2, we have two records, both having same grp id.
In my table, the chain is represented as following
---------------
number grp
---------------
1 1
2 1
2 2
3 2
3 3
4 3
4 4
5 4

But assignemt of grp ids is occuring randomly.
i.e., we might have the same chain as
---------------
number grp
---------------
1 2
2 2
2 1
3 1
3 4
4 4
4 5
5 5

Now how can i derive my original chain (in same order 1-2-3-4-5) using any SQL statement.