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NOT IN vs NOT EXISTS
...o null.
This post explains it very well
http://sqlinthewild.co.za/index.php/2010/02/18/not-exists-vs-not-in/
When the subquery returns even one null, NOT IN will not match any
rows.
The reason for this can be found by looking at the details of what the
NOT IN operation actually means...
Why JSF calls getters multiple times
...ginally posted in PrimeFaces forum @ http://forum.primefaces.org/viewtopic.php?f=3&t=29546
Recently, I have been obsessed evaluating the performance of my app, tuning JPA queries, replacing dynamic SQL queries with named queries, and just this morning, I recognized that a getter method was more...
How many socket connections can a web server handle?
...ic on a single Unix flavoured OS machine - https://blog.whatsapp.com/index.php/2012/01/1-million-is-so-2011/.
And finally, this one, http://highscalability.com/blog/2013/5/13/the-secret-to-10-million-concurrent-connections-the-kernel-i.html, goes into a lot of detail, exploring how even 10 million c...
AngularJS - Value attribute on an input text box is ignored when there is a ng-model used?
..., I can't set the default value of ng-model on the controller because is a PHP form, if server-side validation fails, the form will refresh and whatever is in ng-model will be lost deleting the input value too.
– Luis Elizondo
Sep 30 '14 at 23:39
...
Why does base64 encoding require padding if the input length is not divisible by 3?
...ally it seems you can't, for example the implementations in javascript and php don't support this. Starting with a concatenated string, you either have to decode 4 bytes at a time or split the string after padding characters. It seems like those implementations just ignore the padding chars, even wh...
How to change color of SVG image using CSS (jQuery SVG image replacement)?
...
If you can include files (PHP include or include via your CMS of choice) in your page, you can add the SVG code and include it into your page. This works the same as pasting the SVG source into the page, but makes the page markup cleaner.
The benefit...
What is the difference between a map and a dictionary?
...a, C++
"Dictionary" is used by .Net, Python
"Associative array" is used by PHP
"Map" is the correct mathematical term, but it is avoided because it has a separate meaning in functional programming.
Some languages use still other terms ("Object" in Javascript, "Hash" in Ruby, "Table" in Lua), but ...
Commenting multiple lines in DOS batch file
...heory and test cases in 2 consecutive posts at dostips.com/forum/viewtopic.php?p=14612#p14612.
– dbenham
Mar 30 '12 at 12:29
...
How do I connect to a MySQL Database in Python?
...1 - Setting
You must install a MySQL driver before doing anything. Unlike PHP, Only the SQLite driver is installed by default with Python. The most used package to do so is MySQLdb but it's hard to install it using easy_install. Please note MySQLdb only supports Python 2.
For Windows user, you can...
How much faster is C++ than C#?
...mance of C++ and C#: https://benchmarksgame.alioth.debian.org/u64q/compare.php?lang=gpp&lang2=csharpcore
The bottom line is that C++ gives you much more control over performance. Do you want to use a pointer? A reference? Stack memory? Heap? Dynamic polymorphism or eliminate the runtime o...