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How do I perform the SQL Join equivalent in MongoDB?
...ttps://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup
From the docs:
{
$lookup:
{
from: <collection to join>,
localField: <field from the input documents>,
foreignField: <field from the documents of the "from" collection>...
How to let PHP to create subdomain automatically for each user?
...s the subdomain. You could then retrieve their files and other information based on their account.
This probably isn't as efficient as the ways they list above, but if you don't have access to BIND and/or limited .htaccess this method should work (as long as your host will setup the wildcard for yo...
What is the difference between join and merge in Pandas?
...andas as pd
left = pd.DataFrame({'key': ['foo', 'bar'], 'val': [1, 2]}).set_index('key')
right = pd.DataFrame({'key': ['foo', 'bar'], 'val': [4, 5]}).set_index('key')
left.join(right, lsuffix='_l', rsuffix='_r')
val_l val_r
key
foo 1 4
bar 2 5
The same functi...
How do you execute an arbitrary native command from a string?
... the text to the right.
For example:
MSBuild /t:Publish --% /p:TargetDatabaseName="MyDatabase";TargetConnectionString="Data Source=.\;Integrated Security=True" /p:SqlPublishProfilePath="Deploy.publish.xml" Database.sqlproj
...
How to check if a python module exists without importing it
...mport can find something in python2, using imp
import imp
try:
imp.find_module('eggs')
found = True
except ImportError:
found = False
To find dotted imports, you need to do more:
import imp
try:
spam_info = imp.find_module('spam')
spam = imp.load_module('spam', *spam_info)
i...
What is a singleton in C#?
...Prevent outside instantiation
}
private static readonly Singleton _singleton = new Singleton();
public static Singleton GetSingleton()
{
return _singleton;
}
}
share
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What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
... I understand that it has something to do with having to make a lot of database queries for something that seems simple in the object world.
...
Using NSPredicate to filter an NSArray based on NSDictionary keys
...Swift 3, when you want to filter an array of dictionaries with a predicate based on dictionary keys and values, you may choose one of the following patterns.
#1. Using NSPredicate init(format:arguments:) initializer
If you come from Objective-C, init(format:arguments:) offers a key-value coding ...
Do I need to disable NSLog before release Application?
...Debug configuration add a value to "Preprocessor Macros" value like:
DEBUG_MODE=1
Make sure you only do this for the Debug configuration and not for Beta or Release versions. Then in a common header file you can do something like:
#ifdef DEBUG_MODE
#define DLog( s, ... ) NSLog( @"<%p %@:(%d)&...
Get querystring from URL using jQuery [duplicate]
...o find a solution that had had some testing done on it and covered all the bases (I'm saying that's what he was HOPING to find, not that jQuery would necessarily provide it).
– kghastie
Nov 5 '13 at 22:19
...