I'm making school web application which will be for testing users SQL knowledge and they have to enter SQL queries in form textarea and execute it on server mySQL. the problem that occurred to me is that I can't do prepared statements or binding or white-list on unknown dynamic queries(entered by user) and this makes the application SQL injection vulnerable.  How can I prevent SQL Injection on this type of queries(allowed will be SELECT, DELETE, INSERT, UPDATE) without affecting the final compare result?  Maybe I'm missing some PHP function which can do that? or I have to create a SQL parser which will check user queries for possible SQL injections? I'm not trying to do anything fancy, I just need basic protection for my application.  I use CodeIgniter as Framework, but I don't think this will change anything.  How can I use PDO, statements,whitelists and other techniques, when user can enter queries like   select * from user where some_column = some_value (this is just example)   or query like  select * from user LEFT JOIN ..... having something &gt; 5 ORDER by some_column   I can't predict their input and all possible combinations can contain injection vulnerability.  I receive on my end $_POST['SQL_user_query'] which contains string of SQL query, I can't use on it prepared statement.  EDIT: what i want is that is to prevent the users to do destructive things with my database and gain information about the tables, because after they submit the query the web application also will show the result from the query under the  input textarea and if they make injection that can show sensitive information.
If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?
Some Data Failed to Reconstruct, Motion Tracking I added tracks and stuff, but then when I tried to solve motion track, there was a error that said:     Some Data Failed to Reconstruct   and it also said to look into the console for details, which I did. This is what the console said:    By my understanding, my video is 372 frames long, and Blender is cutting the footage at 318 for some reason. Here is the image of the scene:    Why? Here are links to  and also . Also the next morning I did a camera solve, but then most of the frames went red. 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 Tighten rope without turnbuckles? I have two 4-ft x 4" x 4" wood posts, and each post has a screw eye. There's 12 feet of distance between each post.  How can I tighten a piece of 1/2" diameter rope that goes through each screw eye and it's stretched tightly without having to buy turnbuckles?  There has to be a knot just for this. I am stuck with the following problem.     Prove that $$\limsup_{n \to \infty} (a_n+b_n) \le \limsup_{n \to \infty} a_n + \limsup_{n \to \infty} b_n$$   I was thinking of using the triangle inequality saying $$|a_n + b_n| \le |a_n| + |b_n|$$ but the problem is not about absolute values of the sequence.  Intuitively it's clear that this is true because $a_n$ and $b_n$ can "reduce each others magnitude" if they have opposite signs, but I cannot express that algebraically...  Can someone help me out ? Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'xxx' doesn't support architecture 'i386' Getting below error message while issuing :  sudo apt-get update  Get:1 http://us.archive.ubuntu.com/ubuntu xenial InRelease [95.8 kB] Ign:2 http://repo.mongodb.org/apt/debian wheezy/mongodb-org/3.2 InRelease                                                                                                             Ign:3 http://dl.google.com/linux/chrome/deb stable InRelease                                                                                                                          Hit:4 http://ppa.launchpad.net/canonical-x/vulkan/ubuntu xenial InRelease                                                                                                 Hit:5 http://repo.mongodb.org/apt/debian wheezy/mongodb-org/3.2 Release                                                                             Hit:6 http://us.archive.ubuntu.com/ubuntu xenial-security InRelease                                                   Ign:7 http://dl.google.com/linux/talkplugin/deb stable InRelease                                                      Hit:8 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease                                                    Ign:9 http://linux.dropbox.com/ubuntu wily InRelease                                            Hit:10 http://ppa.launchpad.net/numix/ppa/ubuntu xenial InRelease                               Get:12 http://dl.google.com/linux/chrome/deb stable Release [782 B]       Hit:13 http://dl.google.com/linux/talkplugin/deb stable Release                   Ign:14 https://apt.dockerproject.org/repo ubuntu-wily InRelease           Hit:15 https://apt.dockerproject.org/repo ubuntu-wily Release             Get:16 http://dl.google.com/linux/chrome/deb stable Release.gpg [181 B]   Hit:17 http://linux.dropbox.com/ubuntu wily Release                                   Get:20 http://dl.google.com/linux/chrome/deb stable/main amd64 Packages [1,191 B] Fetched 98.0 kB in 0s (118 kB/s)                                  Reading package lists... Done N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://dl.google.com/linux/chrome/deb stable InRelease' doesn't support architecture 'i386'   This cuts across various releases of ubuntu I have a class like this:  public class myClass {   public List&lt;myOtherClass&gt; anewlist = new List&lt;myOtherClass&gt;;    public void addToList(myOtherClass tmp)   {     anewList.Add(tmp);   }  }   So I call "addToList" a hundred times, each adding a unique item to the list.  I've tested my items to show that before I run the "addToList" method, they are unique.  I even put a line in to test "tmp" to make sure it was what I was expecting.  However, when I do this (lets say myClass object is called tmpClass):  int i = tmpClass.anewList.Count(); for (int j = 0; j&lt;i; j++) {    //write out each member of the list based on index j... }   I get the same exact item, and it's the last one that was written into my list.  It's as if when I add, I'm overwriting the entire list with the last item I've added.    Help?  This makes no sense. I've also tried List.Insert, where I'm always inserting at the end or at index 0.  Still no dice.  Yes, I'm doubly source my indexing is correct and when I do my test I'm indexing through each of the elements.  :)  UPDATE: Okay, I tried this and still had the same problem:  foreach(myOtherClass tmpC in tmpClass.anewList) {         Console.WriteLine(tmpC.theStringInMyClass.ToString()); }   and still for each of the 100 items, I got the same string output... I'm sure I'm doing something completely stupid, but I don't know what yet. I'm still 100% sure that the right string is getting passed in to begin with.  -Adeena    Okay, I tried this and still had the same problem:  foreach(myOtherClass tmpC in tmpClass.anewList) {     Console.WriteLine(tmpC.theStringInMyClass.ToString()); }   and still for each of the 100 items, I got the same string output...  I'm sure I'm doing something completely stupid, but I don't know what yet. I'm still 100% sure that the right string is getting passed in to begin with.  -Adeena When I have .txt files or .py files, I can Quick Look those files in Finder. I have .jl files that are codes written in the Julia Language. Of course they are text files. They will open in a text editor like Sublime Text. How can I Quick Look these .jl files in Finder? Twisted serialport dataReceived() provides fragmented data Is $f(x,y) = |xy|$ differentiable in $(0,0)$? I have no idea how to approach this problem. Should questions include "tags" in their titles? So, I'm working creating a lamp... yes, newbie here.  After modeling for a bit, I noticed that my point of origin was no longer the center of my object:    How to I reset an object origin point to the center of it's geometry? How do I tail a log file and keep tailing it when the latest one changes date? If $\sum a_n b_n <\infty$ for all $(b_n)\in \ell^2$ then $(a_n) \in \ell^2$ I'm trying to prove the following:     If $(a_n)$ is a sequence of positive numbers such that $\sum_{n=1}^\infty a_n b_n&lt;\infty$ for all sequences of positive numbers $(b_n)$ such that $\sum_{n=1}^\infty b_n^2&lt;\infty$, then $\sum_{n=1}^\infty a_n^2 &lt;\infty$.   The context here is functional analysis homework, in the subject of Hilbert spaces.  Here's what I've thought:  Let $f=(a_n)&gt;0$. Then the problem reads: if $\int f\overline{g}&lt;\infty$ for all $g&gt;0,g\in \ell^2$, then $f\in \ell^2$. This brings the problem into the realm of $\ell^p$ spaces.  I know the inner product is defined only in $\ell^2$, but it's sort of like saying: if $\langle f,g\rangle &lt;\infty$ for all $g&gt;0,g\in \ell^2$ then $f\in \ell^2$.  I read this as: "to check a positive sequence is in $\ell^2$, just check its inner product with any positive sequence in $\ell^2$ is finite, then you're done", which I find nice, but I can't prove it :P  From there, I don't know what else to do. I thought of Hölder's inequality which in this context states: $$\sum_{n=1}^\infty a_nb_n \leq \left( \sum_{n=1}^\infty a_n^2 \right)^{1/2} \left( \sum_{n=1}^\infty b_n^2 \right)^{1/2}$$  but it's not useful here. Why is my ethernet interface called enp0s10 instead of eth0? I have been reading about the new Salesforce async triggers. Currently, I tend to handle these sort of needs with a trigger that passes data to a 'Handler class' that would evaluate if a certain change has occurred. If it has then we pass those Ids to a queueable class for further processing.   What advantage do CDC and async triggers offer over using queueable or batch apex? iOS app 1.4.3, iOS 9.2.1  While viewing a post, the app somehow ended up in a state where it refuses to do much of anything.  What does work:   Swipe-scrolling vertically Jumping to the previous / next post using the up / down buttons    Everything else, though, has no effect:   Swipe-scrolling horizontally will not return to the previous view Tapping on a code block will not zoom to code-block view Tapping Delete button to delete a post will show a confirmation dialog, but saying yes will not cause deletion The Add Comment button brings up the text field, but I cannot type anything in it; I can only dismiss it None of the other buttons (Share, More, etc.) do anything Cannot view user profiles or revision history Tapping on links in a post or comment will not show a web page Tapping on a tag shows some visual feedback with a temporary color change, but doesn't do anything else   I still receive push notifications, but tapping on them doesn't take me anywhere. Just wondering if someone can give me an explanation for this capacitor layout - what is it's function? The chip to the right is an ADC.  Circled in blue.    I'm guessing it is well known but i don't know how to search for it. Check if a services is installed using C Can I use variables inside {} expansion without `eval`? Question on showing a bijection between $\pi_1(X,x_0)$ and $[S^1, X]$ when X is path connected. I am trying to do this question taken from Hatchers algebraic topology and I am struggling to understand the notation and the concepts.  As far as I know $\pi_1(X,x_0)$ is the set of end point preserving homotopy classes of loops in X based at $x_0$ and a loop is just a path    $f:I \rightarrow X$ with $f(0)=f(1)$. The question says we can regard $\pi_1(X, x_0)$ as the set of basepoint preserving homotopy classes of maps $(S^1, s_0) \rightarrow (X, x_0)$.   This confuses me, does it mean the set of basepoint preserving homotopy class on maps $g:S^1 \rightarrow X$ which map loops in $S^1$ based at $s_0$ to loops in X based at $x_0$?  Then how can $\pi_1(X,x_0)$ be regarded as this set?  If someone could explain this it would be really useful