为什么这在Python空闲shell中有效，但当我从命令提示符将其作为Python脚本运行时却不行？

Question

这在Python 3.3.2shell中有效

在Python3.3.2外壳中

>>> import datetime
>>> print(datetime.datetime.utcnow())
2013-07-09 19:40:32.532341

这太好了！然后我编写了一个名为“datetime.py”的简单文本文件

内Datetime.py

#Date time
import datetime
print(datetime.datetime.utcnow())
#Prints GMT, which is named Universal Coordinated Time
# Which is UTC because in French it's something like
# Universahl Tyme Coordinatay
#Outputs something like 2013-07-09 15:15:19.695531

证明文件存在

C:\Python33\myscripts>ls
__pycache__  ex1.out  ex2.out  ex3.py    helloworld.py              read1.py
datetime.py  ex1.py   ex2.py   first.py  pythonintoimportexport.py  test.py

这就是它变得神秘的地方！

C:\Python33\myscripts>python datetime.py
Traceback (most recent call last):
  File "datetime.py", line 2, in <module>
    import datetime
  File "C:\Python33\myscripts\datetime.py", line 3, in <module>
    print(datetime.datetime.utcnow())
AttributeError: 'module' object has no attribute 'utcnow'

问题

为什么相同的代码在Python Shell中工作，但在作为脚本运行时不工作？