通过 contact_email 提取到数组并建立索引.由于不能有重复的索引，您将得到最后一次出现:

Extract to an array and index by contact_email. Since there cannot be duplicate indexes you'll get the last occurrence:

$array = array_column($array, null, 'contact_email');

如果您希望将其重新索引回整数:

If you want to re-index that back to integers:

$array = array_values(array_column($array, null, 'contact_email'));