s3 = boto3.client('s3', region_name='eu-central-1')
obj = s3.get_object(Bucket='bucket', Key='Data/data.csv')
df1 = pd.read_csv(obj['Body'])
obj = s3.get_object(Bucket='bucket', Key='Data/data.csv')
df2 = pd.read_csv(obj['Body'])
df = pd.concat([df1, df2])

# date conversion
df.D_TRANS_DATE = pd.to_datetime(df.D_TRANS_DATE, format='%d.%m.%Y %H:%M:%S')
df['D_TRANS_DATE_YEAR']=df['D_TRANS_DATE'].dt.year
df['D_TRANS_DATE_MONTH']=df['D_TRANS_DATE'].dt.month