Why can a database table have only one primary key?
Can I have multiple primary keys in a single table?
Even though I got banned suspended, I'm able to mark a question as a favorite. Is this functionally correct? How to connect a Nokia Lumia 730 to Ubuntu 14.04? Prevent windows from going into sleep when my program is running? How to wrap lines in a jtable cell? OS volume shows as type 'FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF' In the definition of a field one of the required properties is that  every element other than zero has a multiplicative inverse.  It's vague whether the zero is forced not to have an inverse or not, as in is the property  every element other than zero has a multiplicative inverse and zero does not  or  every element other than zero has a multiplicative inverse and zero may or may not?  Regardless, what differences would occur if we adopted one definition as opposed to the other? Prove that any complex matrix can be expressed in term of Hermitian and anti-Hermitian matrices How can we prove that any complex matrix can be expressed in term of hermitian and anti-hermitian matrices of the following form $A = H_1 + iH_2$ Where, $H_1$ is hermitian and $H_2$ is an anti-hermitian matrix What is the iOS alternative to a radio button? Conjugating verbs for nouns referring to groups of people Possible Duplicate:          Frequently when reading tech articles, I see sentences like "Microsoft have released ..." or "Apple have announced ...". This seems wrong to me because the nouns are singular; Microsoft and Apple are individual companies, even though they refer to groups of people. I have not seen this usage outside of tech journalism, but it's pervasive enough that it makes me wonder: is this actually the correct usage?  As a follow-up question, is it correct to use a plural pronoun for a singular antecedent like this? For example, "Apple has announced they are changing their name to Orange" or "Apple has announced it is changing its name to Orange". The second form seems technically correct but sounds awkward. This is a generic inquiry on the common practice/standard for determining the acceptable values of RMS when georeferencing topographic maps.  Is there an absolute value?  Some literature suggests that it should be "less than or equal to 1/2 of the side of a cell which make up the total resolution of the image." With Unix script, I'd like to add values in column 1 if text in column 2 is the same and print the sum.  I have a file that is:    7 GeneA 2 GeneB 6 GeneC 2 GeneB 9 GeneA   I want the output to look like:   16 GeneA 4  GeneB 6  GeneC   Thanks Someone flagged my question as already answered, but it's not I asked a question regarding a very specific feature of a program and whether or not it works with a larger program.  Within hours someone had marked it with "This question may already have an answer here of a similar question, but not related to my question.  The question I asked IS NOT ADDRESSED in the referred-to question. It's frustrating to spend half an hour putting together an intelligent and specific question, and then have someone mark it as a duplicate (or possible duplicate), which apparently causes people to skip over my question. I haven't received any more responses since the question was flagged.   Two questions:  (1) How do I get this flagging removed and (2) what's the best way to prevent these "helpful" flaggings in the future? Unitl now I haven't found the option to enable the curved representation of connectors between nodes. The  doesn't mention such an  option. Is there a keyboard shortcut? Windows 7 Audio Too Loud In Windows 7 (64-bit, Ultimate) the default audio output is extremely high. This has been an issue for a while but I was able to get around it as my previous headphones took more power to drive so it actually worked in my benefit.  However, now I have a set of really sensitive headphones and they're being over-powered. So much so that if I put it down at around 5% of total output it's bearable.  Is there a way I can sort of limit the system's volume so that it's incapable of going extremely loud and then have the rest of it just behave as normal?  Things I've tried:   Uninstalling and re-installing the audio device and drivers. Limiting each application individually. Searching for third-party software (so far nothing looks promising).   The first has no effect. The second works find but I have to do it for every application individually (which can be a pain) and many of them reset their volume every time they're launched, which makes it almost useless. Some even reset the volume while I'm playing a game!  So does anyone have any suggestions on how to make my volume reasonable?  The device is, apparently, a Cirrus Logic CS4206A (AB 24). The computer is an 2010 iMac. Markov's paper on insolubility of the homeorphy problem Just curious whether the process takes a while, and whether it scrapes through history to determine if it was once valid or not. Currently, I have 6 0-vote accepted answers and 20 1+-vote answers (), and that makes it > 5 and > 20% but not for long if voting goes up or down from here. ;-P  Update:  Special thanks to Grace Note for pointing out the  to follow. I upgraded this to a bug because it's been 48 hours during which the criteria supposedly were met. 6 0-votes, 20-23 1+ votes during the whole period. The criteria only last so long, so it may go out of scope soon. If it only checks every 3 days, I'm not sure if that's intentional or a bug. FM Transmitter oscillation problem I've been trying to get this simple FM transmitter to work over the past few days and I could use some help in a few areas.      First iteration was on a breadboard with all parts included.  The exception being I didn't have a 0.1uH coil handy but I had another coil rated at 0.7uH (using my LCR meter).  I also didn't have a C4 value of 4.7pF but I had a 10pF value.  I figured I could just tune it later.  I hooked a scope up to it and got no oscillation.  I tried connecting the probe to the gate and the collector separately and together.  Still no oscillation.  Second iteration.  I removed the audio component of the circuit.  Essentially everything to the left of C2.  I had gotten that working no problem anyway so I figured I would concentrate on the oscillator.  This time I tried different values for the inductor ranging from 20uH to 1mH and different fixed values for the variable cap (10pf, 20pf, 30pf).  These were all ceramic caps. No love.  Third iteration. I tested the transistor to make sure that wasn't the issue.  Seems fine.  PN2222A variety. (Also tried 2N3904 and BC547). I then modeled this up on a piece of perf board.  I even found a SMD inductor of 0.1uH so now I thought I would be good.  Tested all the pieces on the meter before installation. Still nothing. I'm not seeing anything on the spectrum analyzer either.  Questions:   Do you think my benchtop power supply is causing a problem?  All the various versions of this type of FM transmitter circuit on YouTube and the Internet all seem to use a battery.  Any chance the 60Hz main power is messing with things?  I've put .1uF and higher caps on the power rails. I have a 200Mhz SIGLENT SDS1202X-E scope.  I've built and tested other oscillators up to a few MHz before with no issues.  Any thoughts on that being the issue?  I would expect to see something on the scope right? Any chance the probe is dampening the oscillations?     I know there are a lot better FM transmitter circuits out there I was just experimenting with this (and others like it) and couldn't get any to work. What is this story about 20 y.o. inexperienced "kids" fighting against a stronger foe in space? Years ago (mid 90's) I saw a show on network TV, and I'm trying to figure out what the name of it was. The parts of the plot I remember are:   The crew consisted of 20-year-olds (half were women). They were on some mission when they lose their commander. They must then try to get back home, while being tracked down by a foe in a faster, more powerful ship. One of the main characters turns traitor. He's locked up in the brig pending a decision on his fate. He hangs himself, and his body is incinerated by the crew. One of the main characters plays a video game that basically looks like a visor over his face. While playing the game, he's given an idea on how to outwit their foe by using the laser cannon on their ship to create a holographic projection of a larger ship. In the end, they are about to be destroyed by a torpedo launched from the enemy ship.  The torpedo is destroyed by a laser beam from a friendly capital ship that arrives at the last moment.  I remember there being some sort of romance sub-plot to the show as well between two crew members.    Other non-plot details:   This was live action, not animated. I remember the special effects being quite high-end.   The guns on the ships were manipulated by a person sitting in a gunnery chair. This chair projected a holographic view of the fight in front of him/her. From there the gunner used a joystick and a keypad to control the weapons on the ship.  All the crew wore simple Star-Trek style uniforms throughout the entire program, so no jumpsuits or helmets.    I don't know if this was a movie or a TV show, because I never actually saw the beginning of it. I think I saw at least 45 minutes worth, so it could be either as far as I know.   That's all I remember, other than I think the name of the show was fairly generic (something like "Star Command"). I loved the show as a kid even though I only saw it once. I would like to watch it again and see how lame it really was. With left nav, responsive design, and various new-user notices, this is what an anonymous user currently sees (browser window here is 1090px wide):    I realize that a lot of this content -- code of conduct, new-user intro, cookies notice -- is important.  And I get that the left nav is an important design element, and responsive design dictates the width of the right column.  But when you add it all up, Q&amp;A -- what the site is about -- gets a distressingly small portion of the screen.  Can we do better?   Maybe we can make that intro/mini-tour shorter? Maybe we can hide the right column for anonymous users? Maybe some things can wait until the user's viewed a few pages? Maybe other things I haven't thought of?   My concern is that anonymous users -- people coming from Google, people who were referred to a site by users hoping to recruit them, or others who find their way to us but aren't invested in us -- will turn away before seeing how rich and helpful our sites are.  Which would be a real shame, because our sites are awesome.  First impressions matter.  When I'm asking a rabbi to check out Mi Yodeya or a professional chef to check out Seasoned Advice or my vet to check out Pets (all of these have happened), I want to make a good impression.  I want the person to see more than 2.5 questions; I want to increase the chances the person will see something interesting or say "oh I can answer that!" and dig deeper.  Yes, the other stuff is important, but maybe not now?  Is there a better way to "stage" all this information for people we haven't yet hooked? Differences between astronomy, astrophysics and cosmology?