Merging data from 2 query

[eluser]GabrieleMartino[/eluser]
Hello,

I have a table of contacts with user1_id and user2_id.
When I get back the contact list I don't know if the contact is in the left side or right.
I performed 2 query left and right.
I know I can merge the 2 query with array_merge.
Now I need to perform a sort on the column 'email'.
How can I do? I mean how can I make the sort($merged_query,'email')?

Thanks