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Difference between a theta join, equijoin and natural join
I'm having trouble understanding relational algebra when it comes to theta joins, equijoins and natural joins. Could someone please help me better understand it? If I use the = sign on a theta join is it exactly the same as just using a natural join?
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Studies on optimal code width?
...racters. I tend to change it to 120 for no reason other than it was the standard at a company I was with a few years back, and no other company has told me to do it differently.
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Is there a library function for Root mean square error (RMSE) in python?
...lso known as MSE, RMD, or RMS. What problem does it solve?
If you understand RMSE: (Root mean squared error), MSE: (Mean Squared Error) RMD (Root mean squared deviation) and RMS: (Root Mean Squared), then asking for a library to calculate this for you is unnecessary over-engineering. All these me...
How to write iOS app purely in C
...ssage.h>
// This is a hack. Because we are writing in C, we cannot out and include
// <UIKit/UIKit.h>, as that uses Objective-C constructs.
// however, neither can we give the full function declaration, like this:
// int UIApplicationMain (int argc, char *argv[], NSString *principalClassN...
Script entire database SQL-Server
Is there a way I can get a scripting of all tables, procs, and other objects from a database? I know there's an option to script the database but it only gave me some sort of top level script, certainly not a script to create all tables, procs, udfs, .etc.
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Android ClassNotFoundException: Didn't find class on path
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I had the same issue for my project. It happened due to the conflict in android support library version between my project and the library project that I added in my project. Put the same version android support library in your project and library projects you included and clean build... Everythi...
When should I use the Visitor Design Pattern? [closed]
...dmit, I just don't get it. I read the wikipedia article for the pattern and I understand its mechanics but I'm still confused as to when I'd use it.
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How can I change the file type association of an existing file in WebStorm?
I accidentally created a file with no extension and I chose the wrong file type association. Text Document I think. I renamed it to have the .js extension which is what I wanted, but now it's stuck without any syntax highlighting. WebStorm doesn't treat it as a javascript file. I can't find anyw...
Asking the user for input until they give a valid response
...put the input method in a while loop. Use continue when you get bad input, and break out of the loop when you're satisfied.
When Your Input Might Raise an Exception
Use try and except to detect when the user enters data that can't be parsed.
while True:
try:
# Note: Python 2.x users s...
What's the difference between ConcurrentHashMap and Collections.synchronizedMap(Map)?
... properly).
Use the second option if you need to ensure data consistency, and each thread needs to have an up-to-date view of the map. Use the first if performance is critical, and each thread only inserts data to the map, with reads happening less frequently.
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