mysql: if similar row exists set field=1

[jerx]

I am trying to import a buddy list into vb. Unfortunately those entries do not state friend status. Therefore I have to set it manually.

The table looks like this:
user_id contact_id user_ignore friend (=column1, column2, column3, column4)
The friend column was added by myself, because I wanted to use that for the friend status.

Now I would like to set the friend status to 1, if both users have added each other to their buddy list.

Example

If there is an entry like this
1 2 0 0
(user1 added user2 to his buddy list)

it should be turned into
1 2 0 1
(user2 is friend of user1)

if this entry exists
2 1 0 0
(user2 added user1 to his buddy list)

It would even be better to check the ignore column, too. But this would not be as important, because there are only about 100 entries which I could check manually.

Anyone able to help me on this?

Thank you in advance!