SELECT plz.loc_id,
plz.text_val,
ort.text_val
FROM `geodb_textdata` AS plz
RIGHT JOIN
(SELECT loc_id, text_val, text_type
FROM `geodb_textdata`
WHERE text_type = 500100000) AS ort ON plz.loc_id = ort.loc_id
WHERE plz.text_type = 500300000