Add saveguard not to include 0 in a scale for logarithmic axes Including 0 or allowing negative values triggers a bug in the jfreechart logarithmic axis code that causes values < 1 to be drawn in carthesic coordinates. Fixes: flys/issue12345

select.abflusstafel = \
    SELECT ABFLUSSTAFEL_NR, \
           ABFLUSSTAFEL_BEZ, \
           GUELTIG_VON, \
           GUELTIG_BIS, \
           PEGELNULLPUNKT, \
           AT.BFG_ID \
    FROM ABFLUSSTAFEL AT \
    WHERE MESSSTELLE_NR LIKE :number