SQL 请求语法

我有一个这样的查询：

$modifiedDate1 = date("F d Y H:i:s.", filemtime($file));
$query = "INSERT IGNORE INTO file (filename, modifiedDate1) VALUES ".implode(',', $filenames)."".$modifiedDate1."";

我的第二个值的 SQL 语法有误，为什么？

错误：

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'January 01 1970 01:00:00.' at line 1

如果它有帮助，整个代码是：

$pdo = new PDO('mysql:host=localhost;dbname=check', 'root', 'root');
if ($handle = opendir('check')) {
    /* This is the correct way to loop over the directory. */
    while (false !== ($file = readdir($handle))) {
        if($file!='.' && $file!='..') {
            $filenames[] = "('".$file."')";
        }
    }
    closedir($handle);
}
$modifiedDate1 = date("F d Y H:i:s.", filemtime($file));
/* insert new record into the table filenames with the filename */
$query = ("INSERT IGNORE INTO file (filename,modifiedDate1) VALUES ('".implode(',', $filenames)."".$modifiedDate1."')");
$stmt = $pdo->exec($query);   
    if (!$stmt) {
   echo "'nPDO::errorInfo():'n";
   print_r($pdo->errorInfo());
}
    print "finished installing your files!";

此代码用于比较数据库中是否已存在文件的数据。