MySQL WHERE Query and Security Risk
How can I prevent SQL injection in PHP?
Are you less likely to down-vote someone whose gravatar is a photograph of them? I know this is hard to answer since, to the extent that anyone does this, they likely don't do it consciously. In the spirit of Richard Wiseman and  I just wondered what were people's thoughts on it.  Please bear in mind that that's me in the picture, and if you down-vote this, that'll be a real person hurtin', not some abstract symbol. How to prove that if $\lim_{n \rightarrow \infty}a_n=A$, then $\lim_{n \rightarrow \infty}\frac{a_1+...+a_n}{n}=A$ I'm wondering if I have a sufficient proof of the following:   If $(a_n)$ is a sequence such that $\lim_{n \rightarrow \infty}a_n=A$, then $\lim_{n \rightarrow \infty}\frac{a_1+...+a_n}{n}=A$.   My approach:  For all $\varepsilon &gt; 0$, there exists $N$ such that for all $k&gt;N$, $|a_k -A|&lt;\varepsilon$. So we can break the limit up as follows $$\lim_{n\rightarrow \infty} \frac{a_1+...+a_k}{n} + \lim_{n \rightarrow \infty}\frac{a_{k+1}+...+a_n}{n} \overset{\epsilon \rightarrow 0}{=} 0 + \lim_{n \rightarrow \infty}\frac{nA}{n}=A$$  Is this on the right track, or am I missing something about breaking up the limit in the way I have? How to run find -exec? I'd like to find the files in the current directory that contain the text "chrome".  $ find . -exec grep chrome find: missing argument to `-exec'   What am I doing wrong? Provide an easily discoverable way to get the full URL to an answer , clicking &quot;link&quot; &quot;share&quot; for anwers yields a short (traceable) URL in the &quot;share a link to this answer&quot; dialog, such as †:  These short URLs show no clue about the linked question whatsoever. Also, when different people use a short URL for the very same post, then the user id suffix makes those be different URLs for a browser. Such links will then not be shown as visited‡. I know how to get URLs that have a proper slug. But as I see  pop up on these sites (where referrals ), I assume many others just don't realize full URLs would be better for use on these sites themselves? Or many don't want to do the little effort to get the full URL? So: can we please have an easy way to get the full URL as well, in a way that is easily found for those who don't know about the different links? (Currently for questions, clicking &quot;link&quot; has the same effect. But then one can also right-click the title, or take the URL from the location bar, to get the full human-readable URL. Once, Jeff .)  † The short links for answers are not (yet) [automatically converted][6] into a clickable question title either, unlike links such as `https://meta.stackexchange.com/questions/74274/privacy-leak-in-permalink#75963`, which renders as https://meta.stackexchange.com/questions/74274/privacy-leak-in-permalink#75963 But I guess that will change soon.  ‡ On Meta the CSS for posts doesn't indicate such difference anyway, which is a different issue. package makeidx: print first letter for each group of keys I've created index with makeidx package. It works. What really need is to print the first letter above every group of keys (i.e. referring to the image I want to print the red letter, that I have manually inserted). How to move apps from internal to external storage? Where in the DNS process are NS records used? I register a new domain, mynewdomain.com, at a hosting company.   In the advanced DNS settings there is an A record which maps mynewdomain.com to a ip address.  In my webhost control panel, it shows me the nameservers for the domain: ns1.mywebhost.net &amp; ns2.mywebhost.net  When I type in mynewdomain.com into a browser and hit enter I believe the following happens.   ISP resolver searches "." nameserver ISP resolver then told to search ".com" nameserver instead. ISP resolver finds mynewdomain.com, and searches the zone file to get the A record.     So my question is, where does my webhost's nameservers come into play? I believe the flaw in my logic comes from the fact that my zone file (in which the A record is kept) is stored on ns1.mywebhost.net). But if that is the case, how does my ISP resolver know to look here? (because I didn't type this into my address bar) Python Script to Add Fields to Feature Classes I have to try to add a field called 'Name' to a bunch of different feature classes using python, and then access the name of the feature class to fill in the field. I have no idea how to even start this! I know I need a loop but that's all I know. How do you return from 'gf' in Vim I am using Vim for windows installed in Unix mode. Thanks to this site I now use the gf command to go to a file under the cursor.  I'm looking for a command to either:   return to the previous file (similar to Ctrl+T for ctags), or   remap gf to automatically launch the new file in a new window. Proficiency with specific weapons vs 'simple and martial'? In the PHB on pg. 146 it states that there are two weapon categories in which the players can be proficient: simple and martial.  As per  answer to another question, being proficient in either category makes the players character proficient in using all weapons of the respective category.   However in the race descriptions the players are given proficiency for specific weapons. Dwarfs, for example, have the trait Dwarven Combat Training giving proficiency with battleaxes, handaxes, throwing hammers and warhammers.   How do the two types of proficiencies interact with each other? How can I make a deepcopy of a function in Python? How do I retrieve only the needed line from terminal output? I've been building my own emacs because I want to fix some issues in it and get the bug fixes upstream. However, Ubuntu keeps automatically removing my own built emacs and I have to keep rebuilding and reinstalling it.  Here's my output of apt-cache policy emacs when I went to bed last night:  ~/emacs$ sudo apt-cache policy emacs emacs:   Installed: 26.0.50.aaron-1   Candidate: 46.1   Version table:      46.1 500         500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages         500 http://us.archive.ubuntu.com/ubuntu xenial/main i386 Packages  *** 26.0.50.aaron-1 100         100 /var/lib/dpkg/status   Here it is when I wake up:  ~/emacs$ sudo apt-cache policy emacs [sudo] password for excelsiora: emacs:   Installed: 46.1   Candidate: 46.1   Version table:  *** 46.1 500         500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages         500 http://us.archive.ubuntu.com/ubuntu xenial/main i386 Packages         100 /var/lib/dpkg/status   Why is this package being versioned at 46 instead of 24 or 25? 26 is the currently the highest major emacs version you can get.   I can see that this is a meta-package:   Why is Ubuntu updating software without asking?  Main Question: What am I supposed to do - assign my package version a number higher than 46 just to make it stick?   That seems like a horrible hack, or maybe that's how it's supposed to work? Counting points in shapefile within polygons of another shapefile using ArcGIS Desktop? I'm creating a map with two shapefiles:   A polygon of counties Points of cities   I used the function Intersect to group the cities in each county.  I'm trying to get the number of cities in each county to show up in the legend.    For example, in county A there are 16 cities, in county B there are 7 cities and so on.  I'm trying to create a choropleth map that shows the number of cities in each county. I googled it but I couldn't find the answer... maybe I didn't seek it in the proper way. My question is if &quot;to&quot; must be repeated in sentences such as the following ones:   In the past, women used to do the housework and to take care of children.  The aim of this meeting is to control their progress and to discuss the new working plan.    If I had to bet, I would omit the second to... But I am not sure about it. Minecraft crashes on launch with EXCEPTION_ACCESS_VIOLATION, Problematic frame: ig4dev32.dll or ig4dev64.dll or ig4icd32.dll or ig4icd64.dll Handling registration ID changes in Google Cloud Messaging on Android Why am I getting zero divergence of function $\vec{f} = \frac{1}{r^2} \hat{r}$, where $r$ is the distance from the origin and $\hat{r}$ is the unit vector in the radial direction. The divergence of this function over a sphere of radius $R$, which includes the origin.  $$\nabla \cdot f = \frac{1}{r^2} \frac{\partial}{\partial r}(r^2 f_r) = \frac{1}{r^2} \frac{\partial}{\partial r}(r^2 \frac{1}{r^2}) = 0$$ Console flashes on launching, then closes (ms-windows) I installed blender on a windows 7 64 bit system.  I opened it one time then went to the tutorials.  in the meantime I had a power failure and when I tried to start blender again I get a dos window that closes itself then nothing.  I reinstalled Blender and get the same thing.  I am going to try to uninstall then reinstall but in the mean time, any other suggestions are welcome. How to measure supply currents ranging from 1μA to 10mA?