I'm looking for a query to achieve the following:  Current table format   user_id   meta_key    meta_value -------   --------    ---------- 1         address1    abc street 1         city        austin 1         state       TX   Desired output  user_id   address1    city         state -------   --------    ----------   ----- 1         abc street  austin       TX
I've created main SELECT statement like below. For every row in Base table (base on IDKey I've added columns with values from result of INNER JOIN of few tables.  SELECT   IDKey,    Name,    (select Amount from Table1 INNER JOIN Table2 ... where ID=IDKey) AS AmountTypeX,    (select Amount from Table1 INNER JOIN Table2 ... where ID=IDKey) AS AmountTypeY FROM BaseTable   BaseTable:  IDKey Name  ---------- 1     Ian 2     John 3     Ann ...   INNER JOIN of few tables Table1, Table2... :   ID Amount Type -------------- 1  100    X 1  200    Y 2  300    X 2  400    Y 3  500    X 3  600    Y ...   Result looks like:  IDKey  Name  AmountTypeX  AmountTypeY ------------------------------------- 1      Ian   100          200 2      John  300          400 3      Ann   500          600 ...   Do you have any suggestion how to avoid this nested SELECT statements in the main query at the begining and made this query simpler and more effective ?  I wast thinking about PIVOTING of the INNER JOIN result to look like below (all data for particular ID in one row) and then JOIN with main query but Have no idea how to do this and is it possible.  ID  X   Y ----------- 1   100 200 2   300 400 3   500 600 ...
When I press F3 to see the debug screen in I use Minecraft 1.8.1, some information is missing.   Most notably, there are no X, Y, Z coordinates.     What happened to my debug overlay? Let $\int_{- \infty}^{\infty} f(x) dx =1$. Then show that $ \int_{- \infty}^{\infty} \frac{1}{1+ f(x)} dx = \infty.$ How do I get my Mac to boot from an Ubuntu USB key? How to run a complete GUI as root? Say an airplane flies at Mach 1. The doppler effect causes the front of the sound emitted by the plane to reach infinite frequency:    $f = \left ( \frac {343+0}{343-343} \right ) f_0 = ∞$  If the plane suddenly stopped, and there was an observer in front of the sound waves to receive the sound, what would the bunched up waves sound like to the observer? Would they cancel each other out and cause no sound? What is the difference between private and protected members of C++ classes? What is the difference between private and protected members in C++ classes? I understand from best practice conventions that variables and functions which are not called outside the class should be made private—but looking at my MFC project, MFC seems to favor protected. What's the difference and which should I use? The projection of an ellipse is still an ellipse While studying the problem of determining the orbit of a binary star system, my astronomy notes say: "the projection of an ellipse onto a plane is still an ellipse (except the special case in which it's a segment)". How could I prove this?  EDIT: As suggested i'm adding what I know about ellipses. I know the basics of ellipses in the plane, the equation of an ellipse in a plane in cartesia coordinates, the equation of an ellipse in polar coordinates, the fact that ellipses can be obtained by the intersection of planes with a cone. In my geometry course we defined ellipses as the the points of the plane such that the ratio between the distance from a point and a line is constant and less than 1. I also know that the sum of the distances of the points of the ellipse from the foci is constant. MySQL Seems to be crashing quite often, I'd say every hour or so.   The only thing running on this server that is using MySQL is a Drupal installation that I'm working on, there's only one person that's using it and it literally has around three pages - from what I can gather this seems to be a memory issue with innoDB? I'm not great at this stuff so I'm unsure.  Any guidance? Here's the relevant parts from my error.log  140216 14:20:01 [Note] Plugin 'FEDERATED' is disabled. 140216 14:20:01 InnoDB: The InnoDB memory heap is disabled 140216 14:20:01 InnoDB: Mutexes and rw_locks use GCC atomic builtins 140216 14:20:01 InnoDB: Compressed tables use zlib 1.2.3.4 140216 14:20:01 InnoDB: Initializing buffer pool, size = 128.0M InnoDB: mmap(135987200 bytes) failed; errno 12 140216 14:20:01 InnoDB: Completed initialization of buffer pool 140216 14:20:01 InnoDB: Fatal error: cannot allocate memory for the buffer pool 140216 14:20:01 [ERROR] Plugin 'InnoDB' init function returned error. 140216 14:20:01 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 140216 14:20:01 [ERROR] Unknown/unsupported storage engine: InnoDB 140216 14:20:01 [ERROR] Aborting  140216 14:20:01 [Note] /usr/sbin/mysqld: Shutdown complete  140216 14:20:02 [Note] Plugin 'FEDERATED' is disabled. 140216 14:20:02 InnoDB: The InnoDB memory heap is disabled 140216 14:20:02 InnoDB: Mutexes and rw_locks use GCC atomic builtins 140216 14:20:02 InnoDB: Compressed tables use zlib 1.2.3.4 140216 14:20:02 InnoDB: Initializing buffer pool, size = 128.0M InnoDB: mmap(135987200 bytes) failed; errno 12 140216 14:20:02 InnoDB: Completed initialization of buffer pool 140216 14:20:02 InnoDB: Fatal error: cannot allocate memory for the buffer pool 140216 14:20:02 [ERROR] Plugin 'InnoDB' init function returned error. 140216 14:20:02 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 140216 14:20:02 [ERROR] Unknown/unsupported storage engine: InnoDB 140216 14:20:02 [ERROR] Aborting  140216 14:20:02 [Note] /usr/sbin/mysqld: Shutdown complete   EDIT The server is the lowest-spec DigitalOcean Droplet with 512MB RAM. This particular Droplet is running NodeJS, MySQL and Apache. There's a low-traffic static site, a Ghost blog and this Drupal site I'm developing.   Should I just upgrade the RAM, or is there something I can do to fix this? Can I run out of disk space by creating a very large number of empty files? It is well-known that empty text files have zero bytes:    However, each of them contains , which according to my research, is stored in , and do use space.   Given this, it seems logical to me that it is possible to fill a disk by purely creating empty text files. Is this correct? If so, how many empty text files would I need to fill in a disk of, say, 1GB?    To do some checks, I run df -i but this apparently shows the % of inodes being used(?) rather than how much they weigh.  Filesystem             Inodes  IUsed    IFree IUse% Mounted on udev                   947470    556   946914    1% /dev tmpfs                  952593    805   951788    1% /run /dev/sda2            28786688 667980 28118708    3% / tmpfs                  952593     25   952568    1% /dev/shm tmpfs                  952593      5   952588    1% /run/lock tmpfs                  952593     16   952577    1% /sys/fs/cgroup /dev/sda1                   0      0        0     - /boot/efi tmpfs                  952593     25   952568    1% /run/user/1000 /home/lucho/.Private 28786688 667980 28118708    3% /home/lucho I'd like to create a picture like the one with TikZ:    I've already created the electrical part using circuitikz. I'd like to add the part on the right (the motor's shaft with arrows), but don't know how to start, actually. Is there a way to draw 3D shapes, maybe? Or should I draw circles and rotate them?  \documentclass{article} \usepackage{tikz} \usetikzlibrary{intersections} \usepackage{circuitikz} \usepackage{siunitx}  \begin{document}  \begin{figure} \centering \begin{circuitikz} \draw (0,0) to [V, v=$v(t)$, *-*] (0,2)      to [R, l=$R_d$] (2,2)     to [L, l=$L_d$] (4,2)     to [V, v&lt;=$e(t)$] (4,0) to [generic] (4,2) -- (4,0) -- (0,0); \end{circuitikz} \end{figure}  \end{document}   What I have now:   What I'm still missing: Assumptions of linear regression How do you list the primary key of a SQL Server table? Grep: unexpected results when searching for words in heading from man page Quantum mechanics and everyday nature Is there a phenomenon visible to the naked eye that requires quantum mechanics to be satisfactorily explained? I am looking for a sort of quantic Newtonian apple. I know that $$\gcd(a^b-1,a^c-1)=a^{\gcd(b,c)}-1$$ which can be seen by expanding both terms into geometric series. Is there any such simplification for $$\gcd(a^b+1,a^c+1)=?$$  EDIT: When working with polynomials instead of whole numbers, it is $$gcd(x^n+1,x^m+1)=\begin{cases}a^{\gcd(n,m)}+1 &amp; \nu_2(n) =\nu_2(m)\\1 &amp;\text{else}\end{cases}$$ But this gives only a lower bound for the whole-number case. If neutrinos are disfavoured as DM candidates why aren't axions? I saw this question: .  My situation is a little different though.   My target moves, and the shooter moves.  Also, the shooter's velocity is added to the bullets' velocities, i.e. bullets fired while sliding to the right will have a greater velocity toward the right.   What I'm trying to do is to get the enemy to be able to determine where they need to shoot in order to hit the player.  Using the linked SO solution, unless the player and enemy are stationary, the velocity difference will cause a miss.  How can I prevent that?      Here is the solution presented from the stack overflow answer.  It boils down to solving a quadratic equation of the form:  a * sqr(x) + b * x + c == 0   Note that by sqr I mean square, as opposed to square root. Use the following values:  a := sqr(target.velocityX) + sqr(target.velocityY) - sqr(projectile_speed) b := 2 * (target.velocityX * (target.startX - cannon.X)       + target.velocityY * (target.startY - cannon.Y)) c := sqr(target.startX - cannon.X) + sqr(target.startY - cannon.Y)   Now we can look at the discriminant to determine if we have a possible solution.  disc := sqr(b) - 4 * a * c   If the discriminant is less than 0, forget about hitting your target -- your projectile can never get there in time. Otherwise, look at two candidate solutions:  t1 := (-b + sqrt(disc)) / (2 * a) t2 := (-b - sqrt(disc)) / (2 * a)   Note that if disc == 0 then t1 and t2 are equal. Creation and annihilation operators in the hydrogen atom How long can eggs be unrefrigerated before becoming unsafe to eat? Showing order of $Z (G) =1$ or $pq$