大约有 40,000 项符合查询结果（耗时：0.0292秒） [XML]
Is there a REAL performance difference between INT and VARCHAR primary keys?
...(think US States, Country Codes) and a coworker won't budge on the INT AUTO_INCREMENT as a primary key for all tables.
14 ...
What does 'super' do in Python?
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What's the difference?
SomeBaseClass.__init__(self)
means to call SomeBaseClass's __init__. while
super(Child, self).__init__()
means to call a bound __init__ from the parent class that follows Child in the instance's Method Resolution Order (MRO).
If th...
Is there a simple, elegant way to define singletons? [duplicate]
...se the Instance method. Here's an example:
@Singleton
class Foo:
def __init__(self):
print 'Foo created'
f = Foo() # Error, this isn't how you get the instance of a singleton
f = Foo.instance() # Good. Being explicit is in line with the Python Zen
g = Foo.instance() # Returns already ...
How do you do Impersonation in .NET?
...port of Matt Johnson's answer. I added an enum for the logon types. LOGON32_LOGON_INTERACTIVE was the first enum value that worked for sql server. My connection string was just trusted. No user name / password in the connection string.
<PermissionSet(SecurityAction.Demand, Name:="FullTrust")&g...
Flask-SQLAlchemy import/context issue
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The flask_sqlalchemy module does not have to be initialized with the app right away - you can do this instead:
# apps.members.models
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
class Member(db.Model):
# fields her...
Sharing a result queue among several processes
... can I share a queue with asynchronous worker processes started with apply_async ? I don't need dynamic joining or anything else, just a way for the workers to (repeatedly) report their results back to base.
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How to convert vector to array
...?
If you're calling an API function that expects the former, you can do do_something(&v[0], v.size()), where v is a vector of doubles. The elements of a vector are contiguous.
Otherwise, you just have to copy each element:
double arr[100];
std::copy(v.begin(), v.end(), arr);
Ensure not only...
Extract substring in Bash
Given a filename in the form someletters_12345_moreleters.ext , I want to extract the 5 digits and put them into a variable.
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Using Python's os.path, how do I go up one directory?
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os.path.abspath(os.path.join(os.path.dirname( __file__ ), '..', 'templates'))
As far as where the templates folder should go, I don't know since Django 1.4 just came out and I haven't looked at it yet. You should probably ask another question on SE to solve that issue....
Difference between a theta join, equijoin and natural join
... yourself).
** I don't quite know what the result of SELECT * FROM table_expression; is. I know it is not a relation because, among other reasons, it can have columns with duplicate names or a column with no name. I know it is not a set because, among other reasons, the column order is significan...