按部门统计平均工资

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