题解 | 统计快递运输时长

SELECT
    e.exp_type,
    ROUND(AVG(TIMESTAMPDIFF(SECOND,a.out_time,a.in_time))/3600,1) AS time
FROM
    express_tb AS e
    INNER JOIN
    exp_action_tb AS a ON e.exp_number=a.exp_number
GROUP BY
    e.exp_type
ORDER BY
    time;