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What's wrong with nullable columns in composite primary keys?
... word of caution: Having nullable foreign keys is not clean relational database design.
If there are two entities A and B where A can optionally be related to B, the clean solution is to create a resolution table (let's say AB). That table would link A with B: If there is a relationship then it wou...
Ora-00257 错误处理一列 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...列sqlplus assysdba报错ORA-12162切回系统确认系统当前的ORACLE_HOME和ORACLE_SID环境变量[oracle@asdlabdb01~]$echo$ORACLE_HOME空的[oracle...sqlplus /as sysdba
报错ORA-12162
切回系统
确认系统当前的ORACLE_HOME和ORACLE_SID环境变量
[oracle@asdlabdb01 ~]$ echo $ORA...
单页web应用（SPA）的简单介绍 - 更多技术 - 清泛网 - 专注C/C++及内核技术
... main.innerHTML=data;
}
});
}
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参考原文链接：http://www.cnblogs.com/constantince/p/5586851.html
单页应用 SPA
How to do relative imports in Python?
...answering the question.
The problem is that you're running the module as '__main__' by passing the mod1.py as an argument to the interpreter.
From PEP 328:
Relative imports use a module's __name__ attribute to determine that module's position in the package hierarchy. If the module's name does...
Split views.py in several files
...everything is a Python module (*.py). You can create a view folder with an __init__.py inside and you still will be able to import your views, because this also implements a Python module. But an example would be better.
Your original views.py might look like this :
def view1(arg):
pass
def v...
Pythonic way to find maximum value and its index in a list?
...many options, for example:
import operator
index, value = max(enumerate(my_list), key=operator.itemgetter(1))
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Get the current script file name
...
Just use the PHP magic constant __FILE__ to get the current filename.
But it seems you want the part without .php. So...
basename(__FILE__, '.php');
A more generic file extension remover would look like this...
function chopExtension($filename) {
...
Possible to perform cross-database queries with PostgreSQL?
I'm going to guess that the answer is "no" based on the below error message (and this Google result ), but is there anyway to perform a cross-database query using PostgreSQL?
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How to check if std::map contains a key without doing insert?
... Sure, I understand that the OP doesn't care to insert, so a lower_bound-based solution is overkill. I kind of just mentioned my answer "for completeness"; like I said, yours is perfectly adequate. :-)
– Chris Jester-Young
Oct 7 '10 at 23:29
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Dynamically set local variable [duplicate]
... out in the comments there are exceptions, for example classes that define __slots__). Function locals can be optimised for speed because the compiler (usually) knows all the names in advance, so there isn't a dictionary until you call locals().
In the C implementation of Python locals() (called fr...