SQL-Statment

Hi there

I'm trying to compact an imported table.  Any suggestions how this can be done:

Table now:

ID    attr1    attr2
1    5    NULL
1    NULL    7
2    8    NULL
3    NULL    4
4    NULL    NULL

The Result should look like this:

ID    attr1    attr2
1    5    7
2    8    NULL
3    NULL    4
4    NULL    NULL


Thanks for every hint.

Chris