题解 | 支付间隔平均值
select cast(avg(abs(timestampdiff(second,a.time,b.time)))as signed) as gap from order_log a join select_log b using(order_id)
知识点:
1)abs()函数:返回传入参数的绝对值;
2)CAST(expression AS target_type):将一种数据类型的值转换为另一种数据类型
as signed - 整数
as char - 字符串
as demical(10,2) - 2位小数