I need some help, in my database I have a relation many to many, so I created an aux table to make 1 to many relationship, the tables are the next.  offices           request        request_x_offices -------          ---------       ------------------  id               id              id_request office_name      name            id_office   So when i do a query to request_x_offices i get some like the next  request_x_offices ----------------- id_request| id_office ----------------- 1   1 1   2 1   3 1   4 1   5  2   1 2   2  2   3    etc...   after I do a JOIN to replace the offices_id by the name of the office and I get the next  id_request|office_name ----------------- 1 | office_name1 1 | office_name2 1 | office_name3 2 | office_name1 2 | office_name3 2 | office_name5   But I want to get something like the next.  ------ id_request|office_name 1 |office_name1, office_name2, office_name3 2 |office_name1, office_name3, office_name5   I tried do a coalesce but I only get a single row with all the office_name of all the id's :(  Any help will be appreciated, thanks for you time guys.
Consider a database table holding names, with three rows:  Peter Paul Mary   Is there an easy way to turn this into a single string of Peter, Paul, Mary?
Avoid synchronized(this) in Java? How to find real world Selenium projects Where can I find sample or real Selenium projects. All the material I can find on github and on internet are basic, and never intermediate or advanced.  How does a real Selenium project look in real life? How can I find sample code? How can I edit/create new launcher items in Unity by hand? Prove the following equality using mathematical induction: Prove the following equality using mathematical induction: For any integer $n \ge 1$  $$\sum_{i=1}^{n} \frac{1}{i(i+1)} = \frac{n}{n+1}$$  I understand for the base base I need to have $n=1$. If I substituted $n$ for 1 and $i$ for 1 I would get   \begin{align} \sum_{i=1}^{1} \frac{1}{1(1+1)} &amp;= \frac{1}{1+1} \\ \sum_{i=1}^{1} \frac{1}{2} &amp;= \frac{1}{2} \end{align}  As for the inductive step, I inputted $n +1$ but it did not work for me because honestly I did not know what to do with the $i$ and what I should do next.  How would I go about doing the next step and an explanation for $i$ would be helpful. Is there any easy way to open the document library files in a new window or popup depending on the file types?  e.g. PDF - In Adobe reader (currently opens in IE)  Image file (currently opens in IE) Clearly if $\lambda$ is an eigenvalue of $A$ then $p(\lambda)$ is an eigenvalue of $p(A)$ where $p$ is a polynomial. And there are cases where $A$ may have eigenvalues other than these.   Is there a general rule for finding all eigenvalues of $p(A)$? Does it depend on the field from which the elements of $A$ are taken? Are their any partial solutions to this problem? How can I reset or revert a file to a specific revision? I have made some changes to a file which has been committed a few times as part of a group of files, but now want to reset/revert the changes on it back to a previous version.   I have done a git log along with a git diff to find the revision I need, but just have no idea how to get the file back to its former state in the past. Was the singularity at Big Bang perfectly uniform and if so, why did the universe lose its uniformity? How does order-preserving encryption work? Order-preserving encryption (OPE) is, apparently, a method of encrypting data so that it's possible to make efficient inequality comparisons on the encrypted items without decrypting them.  I've been coming across this term in various places (including ) lately, but I have no idea how such encryption schemes are supposed to work.  Any obvious methods I can think of to allow such comparisons on encrypted data would result in catastrophic security failure.  Certainly, I assume that OPE must involve some kind of security tradeoff compared to traditional encryption, but given that it seems to be actively  and , it seems that it must be possible to implement in a way that retains at least some level of useful security.  I just don't see how.  Given that  didn't turn up any convenient Wikipedia articles or other popular summaries of OPE, I figured I'd try asking for one here before diving into the academic literature.  (At worst, I may try to answer my own question later, if nobody else beats me to it.)  So, to summarize, my question is: How does order-preserving encryption work, and what security properties does it provide? Proving the so-called "Well Ordering Principle" Is there anything wrong with the following proof?  Theorem. Every non-empty subset $B \subset\mathbb{N}$ has a least member.  Proof. Assume not. Then, of necessity, we'd have to have $B=\varnothing$, for if $B$ contained even one $b\in\mathbb{N}$, then that $b$ would satisfy $b=min(B). $ Contradiction, end proof.  I get the sense there is something wrong here, but I can't seem to define exactly what. Also, is there a context where one can simply take this principle as an axiom, and not have to prove it? After all, it is extremely intuitive. Thanks. Let $f: \Bbb R \to \Bbb R$ be a differentiable function such that $\sup_{x \in \Bbb R}|f'(x)| \lt \infty$. Then (UGC CSIR-2015, DECEMEMBER, MATHEMATICAL SCIENCES)        $f$ maps a bounded sequence to a bounded sequence.   $f$ maps a Cauchy sequence to a Cauchy sequence.   $f$ maps a convergent sequence to a convergent sequence.   $f$ is uniformly continuous.      I choose all of the options as possible answers because the condition $\sup_{x\in \Bbb R}|f'(x)| \lt \infty$ forces $f$ to be uniformly continuous.(Because $f$ becomes Lipschitz and Lipschitz condition implies uniform continuity)  i.e. $\frac {|f(x)-f(y)|}{|x-y|} \le \sup_{x\in \Bbb R}|f'(x)|$ $ \forall x,y$.  Hence all other options are bound to be true.  Am I correct? How can I change the default "ens33" network device to old "eth0" on Fedora 19? How to get a random value from dictionary? The adjective ones I have heard recently are    forward straightforward forthcoming frank   I was wondering if each of them has positive, negative or neutral meaning?  What are other similar terms that are used for positive, neutral and negative intention? This question is a  of the common question asking for calculus references. It is here to  away the repetition, and give a canonical resource for calculus references.      I'm looking for a resources to learn single-variable calculus. OED says:     doobie: a marijuana cigarette    Origin unknown. A relationship with dobby has been suggested.    dobby/dobbie: A silly old man, a dotard, a booby. Dialectal.      First citations:    1967   J. B. Williams Narcotics &amp; Hallucinogenics. Dubbe, Negro slang for a marijuana roach.    1982   A. Maupin Further Tales of City 95,  I smoke a doobie at lunch.   But I just chanced upon  in Yahoo Answers (don't laugh! :) where someone posted:     "It's obvious that Shaggy's a , I'm sure he's been feeding Scoob a bit of his hash and whatnot."    Scoob = , cartoon "pet" dog of constantly-hungry hippie/village idiot Shaggy (from 1969)   I'm not entirely convinced that 1967 dubbe was necessarily a significant factor in the appearance of  since around 1970 (the hippie era, some might say).  So I'd like to know whether it's credible to claim the usage arose (primarily?) through association with the TV show (specifically, the two characters therein closely associated with marijuana). So assume $Y$ and $X$ are exponentially distributed with parameters $y_1$, and $x_1$ respecitively.  assume c is a constant.  I am having huge trouble to understand the integration of the following expression.  $P(Y&lt;c/u(X))$  $=\int_{t}^{\infty}f_X(x)\int_{0}^{c/u(x)}f_Y(y)dydx +\int_{0}^{t}f_X(x)\int_{c/u(x)}^{\infty}f_Y(y)dydx$  where t is the cross-point that $u(x)$ change sign    here $c/u(x)$ is given by the plot below, t is the point crossing the zero:   Confusion:   I don't understand the second integration of the second term "$\int_{c/u(x)}^{\infty}f_Y(y)dydx$", this isn't right because Y an X only defined for y>0, and x>0. So it's the first quadrant in this plot. A variation on the induced topology (subspace topology) How does the NSAutoreleasePool autorelease pool work? As I understand it, anything created with an alloc, new, or copy needs to be manually released. For example:  int main(void) {     NSString *string;     string = [[NSString alloc] init];     /* use the string */     [string release]; }   My question, though, is wouldn't this be just as valid?:  int main(void) {     NSAutoreleasePool *pool;     pool = [[NSAutoreleasePool alloc] init];     NSString *string;     string = [[[NSString alloc] init] autorelease];     /* use the string */     [pool drain]; } Is it possible to find the origin of a virus? Is there any method with which you can determine the origin for a given piece of malware in Windows?  One of my PCs was recently infected with the  password stealing trojan. Is there any way to tell from what source this virus was downloaded from?