ศิลปิน "Metallica" มีกี่อัลบั้ม?
How many albums does the artist "Metallica" have?
df = pd.DataFrame(columns=['ArtistId']); df2 = pd.DataFrame(columns=['ArtistId', 'Name'])
df[df['ArtistId'].isin(df2[df2['Name'] == 'Metallica']['ArtistId'])].count()