MSSQL, PDO, error when inserting XML string: General error: 102 Incorrect syntax near ‘<?xml version="1.0"

I am trying to insert XML string into a MSSQL database from PHP. I get:

SQLSTATE[HY000]: General error: 102 Incorrect syntax near ‘ (a chunk of the xml follows).

The prepared statement is:

$stmt = $this->db->prepare('
   INSERT INTO [System_XmlExchangeImport] ([Create_ID], [ImportCode], [InputXml]) 
   VALUES (?, ?, ?);
');
$result = $stmt->execute(array('ABCDEFGHKAJSDKLJ', $code, $xml));

The $xml is a valid XML string. The same XML can be inserted OK using an identical statement in an SQL client app (sqlectron)

I have no idea what to do next.

Answer

The problem was caused by encoding. The XML was encoded with Windows-1250, but the database connection was opened with UTF-8 charset:

$connString = "dblib:version=7.0;host=$dbIp:$dbPort;dbname=$dbName;charset=UTF-8;";
$this->db = new PDO($connString, $dbUser, $dbPass);

After changing UTF-8 to WINDOWS-1250 in the DSN ($connString):

$connString = "dblib:version=7.0;host=$dbIp:$dbPort;dbname=$dbName;charset=WINDOWS-1250;";

the XML can be inserted with no problem.