Código PHP:
print "<FORM Name='FCarreras' METHOD='POST' ACTION='MaestroPass.php' TARGET='FrameMiddle' onSubmit='return FnValidaCarr(this);'>";
print "Carrera: <SELECT NAME='Carrera' onChange='FCarreras.submit();' >";
$LcSentencia="SELECT DISTINCT Carreras.IDCarrera, carreras.Nombre FROM Carreras";
$LcVal=mssql_query($LcSentencia);
while ($LcCols=mssql_fetch_array($LcVal))
{ $LcRes=$LcCols['Nombre'];
//$LcRes2=htmlspecialchars($LcRes);
$LcRes2=htmlentities($LcRes);
$LcID=$LcCols['IDCarrera'];
print "<OPTION VALUE=$LcID> $LcRes2";
}
print "</Select><INPUT TYPE='submit' NAME='Boton2' VALUE='»'></table> </form>";