无法从我的数组创建逗号分隔列表

I'm a newbie in PHP. Here's my code:

    $email_db = mysql_query("SELECT emails FROM email_feeds") or die(mysql_error());
    $recipients = array();

    while($row = mysql_fetch_assoc( $email_db )){

        $recipients[] = $row;

    }

    $sendTo = implode(', ', $recipients);
    echo($sendTo);

What I'm trying to do here is get the data from the column emails from the email_feeds table in my database, then put it in an array ($recipients) then echo it in a comma separated form.

E.g. john@mysite.com, mike@mysite.com, claire@mysite.com

My problem is when I run it it shows an "Array to string conversion" notice.

Please help! :)

mysql_fetch_assoc returns an array of columns.
Even though you only have one column, it's still an array containing that one column.

So, when you write this:

$recipients[] = $row;

you're adding a new array to $recipients, not a new string.
Imploding $recipients tries to implode arrays as if they were strings, which they are not.

Try:

$recipients[] = $row['emails'];

Have a read of the documentation for the function you're using.
In particular, pay close attention to the big, red deprecation warning.

You are using mysql_fetch_assoc, which returns an associative array. You really ought to switch to mysqli functions. mysql_ functions are deprecated. When it returns an array, you are assigning an entire array to each element in the recipients array here:

$recipients[] = $row;

What you need is just the string from the array, so you can do this instead:

$recipients[] = $row['emails'];