You can do this like this:
$sql = "INSERT INTO EHS.dbo.T_Kunden_ApArchiv ([KuNr] ,[KontaktName] ,[KontaktVorname] ,
[KontaktpersonPosition] ,[Anrede] ,[Abteilung] ,[OrtsName] ,[KStraße] ,
[KPlz] ,[KTel] ,[KFax] ,[KHandy] ,[Ke-mail] ,[KInternet],
[ArchiviertDurch])
SELECT [KuNr] ,[KontaktName2] ,[KontaktVorname2] ,[KontaktpersonPosition2] ,
[Anrede2] ,[Abteilung2] ,[OrtsName2] ,[KStraße2] ,[KPlz2] ,[KTel2] ,
[KFax2] ,[KHandy2] ,[Ke-mail2] ,[KInternet2], " . $vertriebNr . "
FROM EHS.dbo.T_Kunden
WHERE KuNr = '".$data['kundenNR']."'";
// execute
odbc_exec($db1_link, $sql);
I assumed $vertriebNr
is an integer so i didn't add '
chars around it in query.