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In Postgresql, force unique on combination of two columns
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edited Jan 8 '13 at 18:44
answered Jan 8 '13 at 18:38
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What's the difference between RANK() and DENSE_RANK() functions in oracle?
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248
RANK gives you the ranking within your ordered partition. Ties are assigned the same rank, with ...
Trying to understand CMTime and CMTimeMake
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Peter DeWeesePeter DeWeese
17.4k88 gold badges7373 silver badges9898 bronze badges
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Add column with constant value to pandas dataframe [duplicate]
...with partially aligned indices:
In [7]: from pandas import DataFrame
In [8]: from numpy.random import randint
In [9]: df = DataFrame({'a': randint(3, size=10)})
In [10]:
In [10]: df
Out[10]:
a
0 0
1 2
2 0
3 1
4 0
5 0
6 0
7 0
8 0
9 0
In [11]: s = df.a[:5]
In [12]: dfa, sa = df.ali...
通过API获取IP信息、IP归属地 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...。一、淘宝API接口：http://ip.taobao.com/service/getIpInfo.php?ip=8.8.8.8
{"code":0,"data":{"country":"\u7f8e\u56fd","country_id":"US","area":"","area_id":"","region":"","region_id":"","city":"","city_id":"","county":"","county_id":"","isp":"","isp_id":"","ip":"8.8.8.8"}}
注意：返回...
What is the difference between ~> and >= when specifying rubygem in Gemfile?
...ersion provided and use that until it reaches a maximum version. So ~>0.8.5 is semantically equivalent to:
gem "cucumber", ">=0.8.5", "<0.9.0"
The easy way to think about it is that you're okay with the last digit incrementing to some arbitrary value, but the ones preceding it in the stri...
Types in Objective-C on iOS
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The size of long is: 4.
The size of long long is: 8.
The size of a unsigned char is: 1.
The size of unsigned short is: 2.
The size of unsigned int is: 4.
The size of unsigned long is: 4.
The size of unsigned long long is: 8. ...
“for line in…” results in UnicodeDecodeError: 'utf-8' codec can't decode byte
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428
As suggested by Mark Ransom, I found the right encoding for that problem. The encoding was "ISO-...
Python str vs unicode types
...encoded in a specific encoding to represent the text as raw bytes(e.g. utf-8, latin-1...).
Note that unicode is not encoded! The internal representation used by python is an implementation detail, and you shouldn't care about it as long as it is able to represent the code points you want.
On the c...
How to find out element position in slice?
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answered Nov 29 '11 at 8:09
Evan ShawEvan Shaw
20.1k44 gold badges6262 silver badges5656 bronze badges
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