Using a defined table and column name inside sql query in php
Can PHP PDO Statements accept the table or column name as parameter?
I am trying to write a bash script for testing that takes a parameter and sends it through curl to web site.  I need to url encode the value to make sure that special characters are processed properly.  What is the best way to do this?    Here is my basic script so far:  #!/bin/bash host=${1:?'bad host'} value=$2 shift shift curl -v -d "param=${value}" http://${host}/somepath $@ How do I simplify and evaluate the limit of $(\sqrt x - 1)/(\sqrt[3] x - 1)$ as $x\to 1$? Consider this limit:  $$ \lim_{x \to 1} \frac{\sqrt x -  1}{ \sqrt[3] x -  1}  $$  The answer is given to be 2 in the textbook.  Our math professor skipped this question telling us it is not in our syllabus, but how can it be solved? Quaternions, Rotations and Real numbers I haven't really formally studied Algebra at anywhere near this level, but I was told about the existence of Quaternions a few years ago and I find them really cool. I also like how pure quaternions are analogous to cross products in $R^3$, and that it gives me a way of doing it algebraically rather than relying on hand rules.  Over the course of using them it's my understanding that multiplying an element by another, both imaginary numbers, rotates it in some manner so as to be orthogonal to both, similar to rotations of $\frac{\pi}{2}$ in the space with one real and one imaginary axis when multiplied by $i$, which is why it's useful for cross products as it will rotate it to be orthogonal to a plane spanned by linear combinations of those two vectors [afaik].   What I can't intuit though is why for any pure quaternion multiplication, there's a negative real part [the scalar product] if it's meant to correspond to a rotation within $R^3$ and the space of pure Quaternions is Isomorphic to $R^3$. Similarly I don't understand why $i^2 = j^2 = k^2 = $ A negative real. How do I fix a "Failed to download package files" error? What does this depiction of a black hole in the movie Interstellar mean? I was expecting a whirlpool in 3D and the matter glowing from friction as it nears the center, as I expected a event horizon to be negligible visually.  How does this depiction work? How big is the central sphere? I am puzzled by the perpendicular circles. Are they the event horizons if they are both visible? What would be a path of a particle as it gets swallowed into the singularity? When the ball is being bounced by the goalkeeper from his hands and a player steals it without touching the goalkeeper (while the goalkeeper is not touching the ball) and scores, is it legal or not?   shows what I'm talking about. .NET obfuscation tools/strategy Unparsed HTML shows on search result page Including .eps figure in PDFLatex This question has been asked a lot, but for reason I cannot get it to work. I'd like to include a .eps image in my document - I am using pdflatex in TeXMaker. Below is the input (I am providing the whole preamble incase there is some interference.   \documentclass[11pt]{article} \usepackage{times} \usepackage{graphicx} \usepackage{epstopdf} %converting to PDF \usepackage{amssymb} \usepackage{amsmath} \usepackage{mathtools} \newcommand{\HRule}{\rule{\linewidth}{0.5mm}} \usepackage[parfill]{parskip} \setcounter{secnumdepth}{5} %how deep sections are numbers \usepackage{float} \usepackage[font={sf,footnotesize},labelfont=bf, justification=justified, singlelinecheck=off]{caption} \usepackage[font=footnotesize]{subcaption} \usepackage[scaled]{helvet}  \usepackage{titlesec}  \usepackage[T1]{fontenc} \usepackage[export]{adjustbox} %for large figures \usepackage{upgreek} \usepackage{microtype} \usepackage{setspace} \singlespacing \usepackage[defaultlines=4,all]{nowidow}  \includegraphics[scale=1]{/../model_1_2.eps}    The error I get is:      ! Package pdftex.def Error: File `/model_1_2-eps-converted-to.pdf' not   found.See the pdftex.def package documentation for explanation.Type H    for immediate help.... .../../model_1_2.eps}   I hope someone can help. Are there any simple rules for choosing the definite vs. indefinite (vs. none) article? I can’t for the life of me figure out where to use a and where to use the — and where there is no article at all. Is there a simple rule of thumb to memorize?   The standard rule you always hear:     “If a person knows which item you are talking about then use "the"   . . . doesn’t clear things up for me, as I have no idea whether or not they know. Can you use Dispel Magic on the source of a spell (ie, the caster)? Is Cesaro convergence still weaker in measure? Question of an isomorphism of $\epsilon_ 0$ and a subset of the rationals. When I created my account, I used Facebook Connect as my only login type and I can only log in to my account using it.  I wish to create a Stack Exchange login to be able to log in with instead of Facebook Connect, but I can't find how to do this. It seems that the option for creating a Stack Exchange login is only present when creating a new account? What is a combo update and how is it different than the regular update? Read binary file into a struct I'm trying to read binary data using C#. I have all the information about the layout of the data in the files I want to read. I'm able to read the data "chunk by chunk", i.e. getting the first 40 bytes of data converting it to a string, get the next 40 bytes.  Since there are at least three slightly different version of the data, I would like to read the data directly into a struct. It just feels so much more right than by reading it "line by line".  I have tried the following approach but to no avail:  StructType aStruct; int count = Marshal.SizeOf(typeof(StructType)); byte[] readBuffer = new byte[count]; BinaryReader reader = new BinaryReader(stream); readBuffer = reader.ReadBytes(count); GCHandle handle = GCHandle.Alloc(readBuffer, GCHandleType.Pinned); aStruct = (StructType) Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(StructType)); handle.Free();   The stream is an opened FileStream from which I have began to read from. I get an AccessViolationException when using Marshal.PtrToStructure.  The stream contains more information than I'm trying to read since I'm not interested in data at the end of the file.  The struct is defined like:  [StructLayout(LayoutKind.Explicit)] struct StructType {     [FieldOffset(0)]     public string FileDate;     [FieldOffset(8)]     public string FileTime;     [FieldOffset(16)]     public int Id1;     [FieldOffset(20)]     public string Id2; }   The examples code is changed from original to make this question shorter.  How would I read binary data from a file into a struct? The problem statement is: for $a,b$ coprime, prove that there exists positive integers $x,y$ such that $ax-by=1$.  The question is form Arthur Egnels' problem solving text, and from the chapter on the pigeonhole principle.    My question: His proof begins by generating a list $a,\ldots,a(b-1)$, where he then points out that each element in this list(which proceeds sequentially) doesn't have remainder $0\pmod{b}$.  He then shows that we arrive at a contradiction if we assume that we also don't get remainder $1$ in this list $\bmod b$.  To show the contradiction in this last statement, he first states that we would have positive integers $p,q $ where $ 0&lt;p&lt;q&lt;b$ so that $pa\equiv qa \pmod{b}$.  He then goes on to point out that since we $a$ and $b$ are coprime, we then have that $b| q-p$.  I understand the last part here, but don't see why we get $pa\equiv qa \pmod{b}$.  Thanks in advance There's something funky about some titles in revision histories here on Meta Stack Exchange I've been using the $K$-fold cross-validation a few times now to evaluate performance of some learning algorithms, but I've always been puzzled as to how I should choose the value of $K$.  I've often seen and used a value of $K = 10$, but this seems totally arbitrary to me, and I now just use $10$ by habit instead of thinking it over. To me it seems that you're getting a better granularity as you improve the value of $K$, so ideally you should make your $K$ very large, but there is also a risk to be biased.  I'd like to know what the value of $K$ should depend on, and how I should be thinking about this when I evaluate my algorithm. Does it change something if I use the stratified version of the cross-validation or not? Error on \usepackage {geometry} text property