Suppose we have an EMPLOYEE and a DEPENDENT table. Each employee has an identifier Ssn and possibly a dependent with identifier Essn. Are the following two queries equivalent?  SELECT DISTINCT E.Lname, D.Dependent_name FROM ((EMPLOYEE E) LEFT OUTER JOIN (DEPENDENT D) ON E.Fname=D.Dependent_name);  SELECT DISTINCT E.Lname, D.Dependent_name FROM ((DEPENDENT D) RIGHT OUTER JOIN (EMPLOYEE E) ON E.Fname=D.Dependent_name);   In general, is it true that  (TABLE A) LEFT OUTER JOIN (TABLE B)   is the same as  (TABLE B) RIGHT OUTER JOIN (TABLE A)   ?
Do any queries exist that require RIGHT JOIN, or can they always be re-written with LEFT JOIN?  And more specifically, how do you re-write this one without the right join (and I guess implicitly without any subqueries or other fanciness):   SELECT * FROM t1 LEFT JOIN t2 ON t1.k2 = t2.k2 RIGHT JOIN t3 ON t3.k3 = t2.k3
I saw many saying that the latest version of Ubuntu 16.04 includes an opensource driver for ATI. I have an HP laptop with AMD 6770m + Intel HD 3000 hybrid graphics and wants to install Kubuntu on it. I created a bootable USB drive of Kubuntu 16.04 and booted from it just to check everything works perfectly (I don't want to install it separately and ruin bootloader as of now). But my laptop is getting too hot and the battery is not lasting for more than 30 mins. Also the brightness control is not working at all and it stays high always.   How can I get hybrid graphics on Kubuntu/Ubuntu working well? I am ready to turn off the ATI card since I am not going to play any games on Linux. I just need the Intel graphics + Cool Laptop + Good battery Life + Brightness control.  My BIOS setting for switchable graphics mode is FIXED. Do I need to change it to DYNAMIC?  UPDATE  I wasn't able to make things work in 16.04 so installed 14.04 LTS along with the AMD Catalyst driver. Now everything works perfectly fine. Below are the steps.   Clean install Ubuntu 14.04 LTS Install the fglrx catalyst drivers using “Additional Drivers” window. This will enable us to switch graphics Restart Ubuntu FAN Noise Fix - Refer this  and install i8kutils Brightness Control - Check this     is the official documentation for AMD/Intel hybrid graphics What are weapon damage dice? Following discussion , what constitutes a weapon damage die?  Is it any damage die dealt by the weapon? For example, consider a  longsword.     While the sword is ablaze, it deals an extra 2d6 fire damage to any target it hits.   What are the weapon damage dice? Just the 1d8 from the longsword? Or do the 2d6 Fire damage also count? Paperback novel about a man who kills a birdlike alien on his balcony with a watering can How can I explain how to play D&D to new players without them falling asleep from boredom? Some of my friends just started playing Dungeons &amp; Dragons [5e] for the first time and don't know anything about how to play. I have tried explaining to them the things that are completely necessary and teach them the rest while playing but I could not get them to understand. None of them have a players handbook and they can't afford one and they really want to play. I really want a simple way to explain the basics and since I have a habit of explaining things in ways that are much too complicated. I have already told them the basic rules so all I need to know is a simple way to explain how to play. Redirecting cout to a console in windows I have an application which is a relatively old. Through some minor changes, it builds nearly perfectly with Visual C++ 2008. One thing that I've noticed is that my "debug console" isn't quite working right. Basically in the past, I've use AllocConsole() to create a console for my debug output to go to. Then I would use freopen to redirect stdout to it. This worked perfectly with both C and C++ style IO.  Now, it seems that it will only work with C style IO. What is the proper way to redirect things like cout to a console allocated with AllocConsole()?  Here's the code which used to work:  if(AllocConsole()) {     freopen("CONOUT$", "wt", stdout);     SetConsoleTitle("Debug Console");     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED); }   EDIT: one thing which occurred to me is that I could make a custom streambuf whose overflow method writes using C style IO and replace std::cout's default stream buffer with it. But that seems like a cop-out. Is there a proper way to do this in 2008? Or is this perhaps something that MS overlooked?  EDIT2: OK, so I've made an implementaiton of the idea I spelled out above. Basically it looks like this:  class outbuf : public std::streambuf { public:     outbuf() {         setp(0, 0);     }      virtual int_type overflow(int_type c = traits_type::eof()) {         return fputc(c, stdout) == EOF ? traits_type::eof() : c;     } };  int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) {     // create the console     if(AllocConsole()) {         freopen("CONOUT$", "w", stdout);         SetConsoleTitle("Debug Console");         SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED);       }      // set std::cout to use my custom streambuf     outbuf ob;     std::streambuf *sb = std::cout.rdbuf(&amp;ob);      // do some work here      // make sure to restore the original so we don't get a crash on close!     std::cout.rdbuf(sb);     return 0; }   Anyone have a better/cleaner solution than just forcing std::cout to be a glorified fputc? "He acted strange(ly?)" How can I make Ubuntu 18.04 / 18.10 desktop use Unity (be like Ubuntu 14.04)? I recently installed Ubuntu 18.04 and I'm not keen on the desktop environment. I want the desktop env. I used to have in Ubuntu 14.04. How can I get it?  I've attempted to use , but when I try to install the Unity's 7.2.5 version using the command:  apt install unity=7.2.5   it gives me   E: Version '7.2.5' for 'unity' was not found   For sure I need to add a PPA for this, but which one!? Does Devil's Fruit power gained depend on how much of it is eaten? Luffy accidentally ate the Gomu-Gomu (Rubber-Rubber) fruit, but was interrupted by Shanks after a few bites. It was too late and Luffy got the Devil's Fruit powers anyway. If he had instead eaten the whole of it, would he have got even more power from the fruit? I tried to install Xubuntu 13.10 on an older computer. I noticed some difficulties during installation that may be relevant to my problems. Notably:   The screen resolution was extremely low. The windows were much larger than the screen and I had to move them around to get to the "Next" button. The mouse cursor was a blur of colours that was flashing all the time.   The installation finished and I tried to reboot the computer. Immediately I got:  error: attempt to read or write outside of disk 'hd0'.  Entering rescue mode...  grub rescue&gt;   I made a  USB disk, booted it and chose the default repair. The application told me that the problem is repaired and that If this does not solve my problem I should show  to someone who can help me.  What should I do next? I already tried to install Ubuntu and Xubuntu, both with no success.  EDIT:  I found a workaround.   Insert the Xubuntu live USB Select "try Xubuntu" In the settings menu select "install Xubuntu"   This fixed the problem for me. Since it is solved I cannot test the answer. For positive real numbers $a,b,c$ with $abc = 8$ prove that   $$ \frac{a^2}{\sqrt{(1+a^3)(1+b^3)}} + \frac{b^2}{\sqrt{(1+b^3)(1+c^3)}} + \frac{c^2}{\sqrt{(1+c^3)(1+a^3)}} \geq \frac{4}{3}. $$   Can we prove this by Cauchy-Schwarz or Jensen's inequality? If not how? The number of labelled graphs with all vertices of even degree I have a graph exam tomorrow, and there is a problem that said number of graph with labeled vertices and all of them of even degree is $ 2^{n-1 \choose 2} $.  According to that topic, it means the number of cut spaces is $ 2^{n-1} $. Well, I don't understand what is cut space yet, and why its count is $ 2^{n-1} $ And don't  know why we should divide the total number of graphs by this! Prove that neither $A$ nor $B$ is divisible by $5$ Let the sum   $$ {1+ \frac12 + \frac13 + \frac 14+ \dots +\frac1{99} + \frac 1{100}}$$  be written as $\frac AB$, where $A$ and $B$ are positive integers with no common factors. Show that neither $A$ nor $B$ is divisible by $5$.    Using Mathematica, I found the sum is $$\frac AB=\frac {14466636279520351160221518043104131447711}{278881500918849908658135235741249214‌2272}$$ Can't access global variable inside function Uploading video to youtube in right format I have a Sony CX115 and I have a little footage I'd like to put on youtube. I've downloaded Arista from the Ubuntu Software Center and then I've downloaded its Youtube HD plugin. I've converted my video and uploaded it to youtube... The result is a flashy video with a lot of grey in it:    What could I do to publish it in high quality so it'll be viewable? This is a  about File Permissions on a Linux web server.   I have a Linux web server running Apache2 that hosts several websites. Each website has its own folder in /var/www/.  /var/www/contoso.com/ /var/www/contoso.net/ /var/www/fabrikam.com/   The base directory /var/www/ is owned by root:root. Apache is running as www-data:www-data. The Fabrikam website is maintained by two developers, Alice and Bob. Both Contoso websites are maintained by one developer, Eve. All websites allow users to upload images. If a website is compromised, the impact should be as limited as possible.  I want to know the best way to set up permissions so that Apache can serve the content, the website is secure from attacks, and the developers can still make changes. One of the websites is structured like this:  /var/www/fabrikam.com     /cache     /modules     /styles     /uploads     /index.php   How should the permissions be set on these directories and files? I read somewhere that you should never use 777 permissions on a website, but I don't understand what problems that could cause. During busy periods, the website automatically caches some pages and stores the results in the cache folder. All of the content submitted by website visitors is saved to the uploads folder. Proving that $\arctan(x)+\arctan(1/x)=\pm \pi/2$, could this line of reasoning possibly be correct? Increasing extent of Raster? I need to parse  strings like "2008-09-03T20:56:35.450686Z" into Python's datetime type.  I have found  in the Python standard library, but it is not very convenient.  What is the best way to do this? What's the source of "shipped" in a romantic sense? I'm trying to figure out a recursive formula for the number of possible distinct binary trees at any depth d. I haven't been able to find any sort of sources on this.  basically, at depth 0, the only binary tree is the empty one so 0, 1  then at depth 1 the only possibility is a single node so 1, 1  at depth = 2 there are 3 possibilities, and at depth 3 I counted 21 possibilities.  I haven't been able to figure out some recursive reasoning for what 4 could be and so on. The only thing I have in place is that there will always be 1 for the full tree.