如何转换为3位小数

Question

我创建了这个查询来查找行驶里程的平均值，但我正在努力将数据格式化为小数点后 3 位。

49.614112472330234

SELECT AVG(Mileage_Used)/SUM(time_to_sec(timediff(Lesson_Finish_Time,Lesson_Time))/3600) as Mileage_per_hour from LESSONS;

Answer 1

将值转换为具有正确精度的十进制类型：

select cast(<yourvalue> as decimal(10,3))

在你的情况下：

SELECT cast(AVG(Mileage_Used)/SUM(time_to_sec(timediff(Lesson_Finish_Time,Lesson_Time))/3600) as decimal(10,3)) as Mileage_per_hour 
from LESSONS