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MongoDB sort排序、index索引教程 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...排列。
语法
sort()方法基本语法如下所示：
>db.COLLECTION_NAME.find().sort({KEY:1})
注意：
即使键值写错了（即文档中没有该键值），命令本身不会报错，当然排序也没有效果。
实例
col 集合中的数据如下：
{ "_id" : ObjectId("56066542...
Is there a short contains function for lists?
...her have said, you may also be interested to know that what in does is to call the list.__contains__ method, that you can define on any class you write and can get extremely handy to use python at his full extent.
A dumb use may be:
>>> class ContainsEverything:
def __init__(self):...
Python: How do I make a subclass from a superclass?
...
# Initialize using Parent
#
class MySubClass(MySuperClass):
def __init__(self):
MySuperClass.__init__(self)
Or, even better, the use of Python's built-in function, super() (see the Python 2/Python 3 documentation for it) may be a slightly better method of calling the parent for ...
Loading Backbone and Underscore using RequireJS
...bone and Underscore, it seems kind of tricky. For one, Underscore automatically registers itself as a module, but Backbone assumes Underscore is available globally. I should also note that Backbone doesn't seem to register itself as a module which makes it kind of inconsistent with the other libs. T...
Determine if Python is running inside virtualenv
...r sys.base_prefix did not ever exist. So a fully robust check that handles all of these cases could look like this:
import sys
def get_base_prefix_compat():
"""Get base/real prefix, or sys.prefix if there is none."""
return getattr(sys, "base_prefix", None) or getattr(sys, "real_prefix", No...
Why does sun.misc.Unsafe exist, and how can it be used in the real world?
...
VM "intrinsification." ie CAS (Compare-And-Swap) used in Lock-Free Hash Tables
eg:sun.misc.Unsafe.compareAndSwapInt
it can make real JNI calls into native code that contains special instructions for CAS
read more about CAS here http://en.wikipedia.org/wiki/Compare-and-swap
The sun.misc.Unsafe fu...
How do I store an array in localStorage? [duplicate]
...
if you needed all of them how would you retrieve them?
– Dvid Silva
Nov 16 '13 at 23:29
...
Why is semicolon allowed in this python snippet?
...ot warrant the use of semicolons to end statements.
So why is this (below) allowed?
15 Answers
...
Are the PUT, DELETE, HEAD, etc methods available in most web browsers?
...eation of a new web
page resource, the updating of the existing page, or all of the
mentioned outcomes.
The keyword dialog, mapping to the state dialog, indicating that
submitting the form is intended to close the dialog box in which the
form finds itself, if any, and otherwise not subm...
Python executable not finding libpython shared library
I am installing Python 2.7 on CentOS 5. I built and installed Python as follows
9 Answers
...