按物种统计平均花瓣长度

def solve():
    import sqlite3
    import pandas as pd
    conn = sqlite3.connect(':memory:')
    df = pd.read_csv('https://liangdaima.com/static/data/ds_iris.csv')
    df.to_sql('iris', conn, index=False)
    result = conn.execute('SELECT species, AVG(petal_length) AS avg_len FROM iris GROUP BY species').fetchall()
    conn.close()
    return result