Error binding parameter 0 - probably unsupported type.

[illmattic]

I found a different way to achieve the desired result:

api_key = open('quandlapikey.txt', 'r').read()

def data_extract(code, column_name):
    data = quandl.get(code, authtoken=api_key, start_date='2000-01-01', collapse='monthly',)
    data['Y/Y, (%)'] = data['Value'].pct_change(12)*100
    data.rename(columns={'Value': column_name}, inplace=True)
    return data

m2 = data_extract('FRED/M2','M1')
m1 = data_extract('FRED/M1','M1')
mb = data_extract('FRED/BOGMBASEW', 'Monetary Base')

df_merged = [mb,m1,m2]
df = reduce(lambda  left,right: pd.merge(left,right,on='Date', how='outer'), df_merged).fillna('-')

conn = sqlite3.connect('Database.db')
c = conn.cursor()

def data_entry():
    df.to_sql('US Money Supply', conn, if_exists='replace')
    conn.commit()
    c.close()
    conn.close()

data_entry()

Here I get no errors and the output I wanted.