I have chosen to ask this question via an example as I think it most clearly illustrates what I am trying to do. 

Say I have the following table:

```
member   number  time
------   -----   -----
  1        2     19:21 
  1        4     19:24 
  1       27     19:37
  2        4     19:01
  2        7     21:56
  2        8     22:00
  2        21    22:01

```

How can I obtain the following column?

```
member   number  new column
------   -----   ---------
  1        2       2.4.27 
  1        4       2.4.27
  1       27       2.4.27
  2        4       4.7.8.21
  2        7       4.7.8.21
  2        8       4.7.8.21
  2       21       4.7.8.21

```

EDIT(S):

I am using DB2 SQL.

There is not necessarily the same number of rows for each member.

The order is determined by time say.