dataframe merge

[gunther]

hello, i am a little bit frustrated with merge.

I habe two tables:

PZN | Name | Anzahl
1234 | Aspirin | 1
2345 | Mexalen | 2
4567 | Sinupret |9
4567 | Sinupret |2

and

PZN | MB | Zeichen
1234 | 1| +
2345 | 2| ++
4567 | 0| ++

I would like to merge the two tables with "PZN" and only column MB from second table
so that I get

PZN | Name | Anzahl | MB
1234 | Aspirin | 1 |1
2345 | Mexalen | 2 |2
4567 | Sinupret |9 |0
4567 | Sinupret |2 |0

How do I achieve this?