Filter mysql results based on checkboxes - mysql

Question

I am trying to filter mysql results based on checkboxes that have been ticked. My query works on the first check but returns nothing on the second filter. My checkbox array is $_POST['country'] which I implode in the GetSQLValueString function to create the comma separated values - (United Kingdom, France) etc. I am using the MySQL IN clause for the multiple selections.
I need it to filter multiple country selections
if (isset($_POST['country_submit']) && $_POST['country'] != '') {
mysql_select_db($database_tub, $tub);
$query_trade = sprintf("
SELECT u.user_id,
u.contact_person,
u.company,
u.country,
u.pic_small,
u.website,
SUM(u.trader_or_bond = %s
AND t.user_id IS NOT NULL) AS count
FROM users u
LEFT JOIN trading t ON u.user_id = t.user_id
WHERE u.trader_or_bond = %s AND u.country IN(%s)
GROUP BY u.user_id
ORDER BY COUNT(t.user_id) DESC",
GetSQLValueString('trader', "text"),
GetSQLValueString('trader', "text"),
GetSQLValueString(implode(',', $_POST['country']), "text"));
$trade = mysql_query($query_trade, $tub) or die(mysql_error());
}

Answer 1

I have come up with this but not sure if safe for MySQL injection plus its not as clean as I would like.
if (isset($_POST['country_submit']) && $_POST['country'] != '') {
$SingleQuotes = "'".implode("', '", array_map('mysql_real_escape_string', $_POST['country']))."'";
mysql_select_db($database_tub, $tub);
$query_trade = sprintf("
SELECT u.user_id,
u.contact_person,
u.company,
u.country,
u.pic_small,
u.website,
SUM(u.trader_or_bond = %s
AND t.user_id IS NOT NULL) AS count
FROM users u
LEFT JOIN trading t ON u.user_id = t.user_id
WHERE u.trader_or_bond = %s AND u.country IN($SingleQuotes)
GROUP BY u.user_id
ORDER BY COUNT(t.user_id) DESC",
GetSQLValueString('trader', "text"),
GetSQLValueString('trader', "text"));
$trade = mysql_query($query_trade, $tub) or die(mysql_error());
}