I am trying to use the stuff function in MS SQL to stuff certain info. Here is the example:  Number          Value  1                 1 2                 1 3                 1 1                 2 2                 2 3                 2 1                 3 2                 3   I would like to stuff the column so that only one record will display as following:  Value             Number 1                 1,2,3 2                 1,2,3 3                 1,2   Please note that there are a like n-Numbers and n-Values.
Using MySQL, I can do something like:  SELECT hobbies FROM peoples_hobbies WHERE person_id = 5;   My Output:  shopping fishing coding   but instead I just want 1 row, 1 col:  Expected Output:  shopping, fishing, coding   The reason is that I'm selecting multiple values from multiple tables, and after all the joins I've got a lot more rows than I'd like.  I've looked for a function on  and it doesn't look like the CONCAT or CONCAT_WS functions accept result sets.  So does anyone here know how to do this?
When deriving the quadratic equation as shown in the  () the main proof contains the step: $$ \left(x+{\frac {b}{2a}}\right)^{2}={\frac {b^{2}-4ac}{4a^{2}}} $$ the square root is taken from both sides, so why is  $$\sqrt{4a^2} = 2a$$  in the denominator and not $$ \sqrt{4a^2} = 2\left |a  \right | $$ Could somebody explain this to me? Thank you very much Norman Window Optimization A finite, cancellative semigroup is a group Let $G$ be a finite, nonempty set with an operation $*$ such that   $G$ is closed under $*$ and $*$ is associative Given $a,b,c \in G$ with $a*b=a*c$, then $b=c$. Given $a,b,c \in G$ with $b*a=c*a$, then $b=c$.   I want to prove that $G$ is a group, but I don't know how to show that there exists an identity $e\in  G$ such that $e*x=x$ and $x*e=x$ $\forall x \in G$. I also don't know how to show that $\forall$ x $\in G$ there exists a $y \in G$ such that $y*x=e$ and $x*y=e$. How do I do this? Pass by Reference / Value in C++ I would like to clarify the differences between by value and by reference.  I drew a picture     So, for passing by value,  a copy of an identical object is created with a different reference, and the local variable is assigned the new reference, so to point to the new copy  How to understand the words: " If the function modifies that value, the modifications appear also within the scope of the calling function for both passing by value and by reference "  Thanks! How to install "vanilla" TeXLive on Debian or Ubuntu? Get Source Code from an .apk file? How to access QGIS Plugin Repositories from behind a proxy? I have been trying to teach myself QGIS by using this forum and others to help. Most of my questions can be answered by downloading plugins that are available through 3rd party repositories but for some reason I am not able to connect with these. Anyone have any ideas why this is the case? Make 15 lines / ticks with Photoshop, each of them rotated of 20° Calculating sequential numbers into sorted table using ArcGIS Desktop? Is there a way to calculate a sorted field with sequential numbers?  I have seen  that outlines how to calculate sequential numbers, but this is always calculated on FID order, not on sorted order.  #Pre-logic Script Code: rec=0 def autoIncrement():      global rec      pStart = 1       pInterval = 1      if (rec == 0):           rec = pStart       else:           rec += pInterval       return rec  #Expression: autoIncrement()   An example of what I'm trying to do.  I've used an advanced sort to sort by year, month, day, and now want to have sequential numbers in the Seq field.  You'll see that my OBJECTID field is not in order, so the above code won't work.    Can this be done either in the Field Calculator or using an Update Cursor in arcpy? How can I install applications like Google Chrome on Ubuntu?  Are there any commands to install an application?    Index of answers: Is it possible to set the "urgent" flag in Gmail for outgoing mail? I'd like to be able to flag time-sensitive emails as such. Finding the asymptotic of an integral I came across the following exercise on asymptotic behavior of integrals: $$I(a) = \int_0^\infty\frac{\cos x}{x^a} \, dx, \text{ where } a\to0^+.$$ I have tried integrating by parts or replacing $\cos x$ with the first summands of its Taylor series, but I end up with something equal to infinity (independent of $a$ and that is not what we want).  I just thought about the substitution $x \leftrightarrow\frac{1}{1+x^2}$ and I get the  following result:  $$I(a) = \frac{\cos(1/2)}{2^{2-a}} + \int_0^1\frac{2x^3 \cos\left(\frac{1}{1+x^2}\right)}{(1+x^2)^{3-a}} \, dx - \int_0^1 \frac{2x^3\sin\left(\frac{1}{1+x^2}\right)}{(1+x^2)^{2-2a}}\,dx$$ If I could prove that the last summands are $o(I(a))$ then it would be OK, but I think, in general my strategy won't work. Apparently this is supposed to be an easy exercise, but I can't come up with anything right now. $\infty = -1 $ paradox problems installing mathtools error with inner class object Electric circuits in TeX, LaTeX, and Friends What are some ways to draw electric circuits in TeX systems?  I'm making this community wiki since I haven't found a question related to this.  I was thinking along the lines of . What do you think of that? Other examples are more than welcome, of course. No space left on device -- but there is space I'm running an Ubuntu 12.04.1 server in a VMware virtualized environment that has a strange issue. Twice now, at seemingly random times, the machine has suddenly been unable to write to the root partition despite plenty of space seemingly available. I'm at a loss trying to figure out what's wrong.  "df -h" shows all mounted volumes with 40% or more free space. Both times this has happened, rebooting resolved it for a few minutes, and then it was back to saying "no space left on device." Restoring it from a snapshot seems to fix it for longer, but since this has now happened again, I'm not sure what to do with it.  If it helps, the machine is a network print server running CUPS 1.5.3 and Samba 3.6.3. Do I need a UK visa? How and where to apply? URLs are linked despite being inside a code span Markdown source:  `http://google.com`  - `http://google.com`     - `http://google.com`   Rendered result:  http://google.com   http://google.com   http://google.com    Note that the third code span is a link. Adding a newline before the list item makes the link disappear. Why does English spelling use silent letters? Why have a letter in a word when it’s silent in pronunciation, like the b in debt?  Can anyone please clarify my uncertainty here?