jQuery Forum

OK, I'll take a shot.
Its hard to comment on the first block of code when the meaty part of it is  //Pull in the data,  but it looks OK, and if you can see accurate response and JSON fields in Firebug, then its fine.

The second block of code is suspicious to me because it is home rolled JSON encoding. It may be right, or maybe not in some cases.  Here is more conventional code that uses well tested PHP functions. Maybe it will help. In either case, take a look at Firebug's console to see the response you are getting.

    $fetch = mysql_query("SELECT DISTINCT neighborhoods, borough FROM places.neighborhoods
                          WHERE city='$city' AND stateProvinceAbbreviation='$state' AND countryAbbreviation='$country'
                          AND neighborhoods LIKE '". mysql_real_escape_string($_POST['term']) ."%'

                          LIMIT 0,7");
                         
    /* If no query result / no rows returned by the query, return null to the client. */
    if(mysql_num_rows($fetch) == 0)
    {
    return;
    };
    /* return called without any value, returns null */

                         
    /* Retrieve the query results and store in an array. Specify a MySQL associative array with case sensitive field names.*/
        while ($row = mysql_fetch_array($fetch, MYSQL_ASSOC))
        {
    /* In each row, pull neighborhoods and borough. */
            $row_array['name'] = $row['neighborhoods'];
            $row_array['value'] = $row['neighborhoods'];
            $row_array['borough'] = $row['borough'];
           
            array_push($return_arr,$row_array);
        }
}
/* Toss back neighborhood results as a json encoded array. */
echo json_encode($return_arr);
/* Free connection resources. */
mysql_close($conn);

The third block of code looks OK, but I'm not infallible.

On another point, the use of trim and strip_tags does not provide security.  Its better to use mysql_real_escape_string(), as in my $fetch statement above.

3 thoughts:
1. In Firebug or Chrome Developer Tools, what does Console show you when the POST (or maybe you use GET) statement appears when the server delivers the JSON?  Click on the +sign and then on the response and JSON tabs to check if there is content, and if it is correctly formatted.  Copy any content and paste it into jsonlint to check for proper JSON format.

2. I don't see a dataType: json, statement in the 1st block. Don't know how it worked without it, but maybe 1.9.1 requires it.

3. I wonder about the source: "ajax/clientlist.php" statement in your first block of code. It may have worked in 1.8.18, but I question whether it is proper to fire an ajax session with your server.  Did you get that expression out of jQuery documentation? If so, where, so I can look at it.

FWIW, here is a link to a prior post of mine. Scroll down and you'll find a different pattern for setting up an ajax session in the source: option.  It works.

https://forum.jquery.com/topic/autocomplete-how-to-use-mysql-data