大约有 48,000 项符合查询结果（耗时：0.0837秒） [XML]
Retrieve only the queried element in an object array in MongoDB collection
...r to filter an array during projection, which has the benefit of including all matches, instead of just the first one.
db.test.aggregate([
// Get just the docs that contain a shapes element where color is 'red'
{$match: {'shapes.color': 'red'}},
{$project: {
shapes: {$filter: {
...
What does -D_XOPEN_SOURCE do/mean?
...ch one you need (if any) by looking at the man page for each function you call.
For example, man strdup says:
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
strdup(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500
strndup(), strdupa(), strndupa():...
Efficiently convert rows to columns in sql server
...d than just a single script but gives you much more flexibility.
First of all There are 3 objects:
User defined TABLE type [ColumnActionList] -> holds data as
parameter
SP [proc_PivotPrepare] -> prepares our data
SP [proc_PivotExecute] -> execute the script
CREATE TYPE [dbo].[ColumnAc...
Super-simple example of C# observer/observable with delegates
...
The observer pattern is usually implemented with events.
Here's an example:
using System;
class Observable
{
public event EventHandler SomethingHappened;
public void DoSomething() =>
SomethingHappened?.Invoke(this, EventArgs.Empt...
Equals(=) vs. LIKE
...tify an example where these operators produce obviously different results. Allow me to quote from the MySQL manual:
Per the SQL standard, LIKE performs matching on a per-character basis, thus it can produce results different from the = comparison operator:
mysql> SELECT 'ä' LIKE 'ae' COLLA...
How to keep the console window open in Visual C++?
...ause") or any other garbage. Changing this works.
– Callat
Apr 22 '16 at 16:08
Ctrl+F5 means 'Start Without Debugging'...
How to run functions in parallel?
...find an answer to my question. I am trying to run multiple functions in parallel in Python.
6 Answers
...
What's the proper way to install pip, virtualenv, and distribute for Python?
...estion 4314376 , I recommended using ez_setup so that you could then install pip and virtualenv as follows:
15 Answer...
Get notified when UITableView has finished asking for data?
...eload its data. So, when the second NSLog is fired, the table view has actually finish asking for data.
I've subclassed UITableView to send methods to the delegate before and after reloadData. It works like a charm.
share
...
python setup.py uninstall
I have installed a python package with python setup.py install .
16 Answers
16
...