PHP按键替换数组值

I have an array:

我有一个数组：

 Array
(
    [0] => Array
        (
            [id] => 11
            [email_theme_id] => 1_5
            [email_template] => Array()
            [add_template] => 
            [email_template_subject] => Your free and bargain ebook alert for Sunday
            [last_update] => 1392314609
        )

    [1] => Array
        (
            [id] => 10
            [email_theme_id] => 2_12
            [email_template] => Array()
            [add_template] => 
            [email_template_subject] => Your free and bargain ebook alert for Sunday
            [last_update] => 1392314609
        )

)
 Array
(
    [0] =