PHP array copy certain keys, built-in functions? Nested loop performance?

Question

I have a PHP array that I\'d like to duplicate but only copy elements from the array whose keys appear in another array.

Here are my arrays:

$data[123] =         


        

Answer 1

Why not load the entire result set into an array, then begin processing with nested loops?

$query_result = mysql_query($my_query) or die(mysql_error());
$query_rows = mysql_num_rows($query_result);
for ($i = 0; $i < $query_rows; $i++)
{
    $row = mysql_fetch_assoc($query_result);
    // 'key' is the name of the column containing the data key (123)
    // 'value' is the name of the column containing the value (aaa)
    $data[$row['key']] = $row['value']; 
}
foreach ($data as $key => $value)
{
    if ( in_array($key, $keys_to_copy)) 
    {
        $copied_data[$key] = $value;
    }
}