php mysql通过第一个首字母搜索

$letter = mysql_real_escape_string($letter);
$sql = \"SELECT ID, FirstName, LastName FROM stafftest WHERE FirstName LIKE \'\" . $letter . \"%\' 
OR LastName LIKE \'\" . $letter .\"%\'\";

/* $db_connection is assumed to be a mysqli connection resource */

$query = $db_connection->prepare(\'SELECT ID, 
                                         FirstName, 
                                         LastName 
                                  FROM   stafftest 
                                  WHERE  FirstName LIKE ? 
                                  OR     LastName LIKE ?\');
$search = $letter . \'%\';
$query->bind_param(\'s\', $search);
$query->execute();

\"SELECT ID, FirstName, LastName FROM stafftest 
 WHERE FirstName REGEXP \'^\".$letter.\"\' OR 
       LastName REGEXP \'^\".$letter.\"\'\";