appending a value to array from a query

[toodi4]

I don't know why, but I often seem to have a mental block when it comes to arrays.
I think what I'm trying to do is fairly simple, but I just can't quite figure it out:

I have existing arrays of user information:

( [name] => Bob [dob] => 1981-02-10 [sex] => M [flags] => 7 )

( [name] => Bruce [dob] => 1986-03-22 [sex] => M [flags] =>6 )

etc.

Then I run a mysql query that creates another set up arrays:

( [username] => bob [accepted] => 1 [registered => 1[timestamp] => 1203452126 )

I want to append just the value of 'registered' to the first array. The query might return a different amount of rows in different order from the first, so it should append a value only where name=username.

What is the proper way to do this?

Thanks!

[laserlight]

You could try something along these lines:

foreach ($array as $row) {
    if (($key = array_search($row['username'], $existing_array)) !== false) {
        $existing_array[$key]['registered'] = $row['registered'];
    }
}

My main gripe is that this is a quadratic time algorithm, so it is potentially rather slow.