mysql_fetch_row() error but why
mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc... expects parameter 1 to be resource
How to prove $(-3) \times (-4) = 12$? How to logically understand the multiplication of two integers ?  Eg:  3 x 4 = 12 (is understandable)  -3 x4 = -12 (is also somewhat understandable)  But , 3 x -4 = -12 (is NOT understandable)  -3 x -4 = 12 (is also NOT understandable)  Now , at this we must assume that commutative property may not be true .  What is the logical explanation for something being multiplied negative times ? Let $C$ be the Banach space of all complex continuous functions on $[0,1]$ endowed with the supremum norm. Let $B$ be the closed unit ball of $C$. Does there exist a $\Lambda\in C^*$ for which $\Lambda (B)$ is open? Note that $C$ is a locally convex space and $B$ is convex, balanced and closed set, by the separation theorem of convex sets,we know there exists $\Lambda\in C^*$ such that $|\Lambda f|\leq 1$ for all $f\in B$ and $|\Lambda f|&gt;1$ for $f\in B^c$. But how about this when we consider some concrete space above? Joining Excel table to shapefile in ArcMap? I have a shapefile of lower layer super output areas (LSOA) for England and Wales and I have a spreadsheet of the indices of deprivation for each of the LSOA's in England. I want to join the deprivation data to the shapefile so it can be mapped in ArcMap. I tried joining the table through the Join and Relates > Join option and put in the fields for the LSOA data for both shapefile and spreadsheet (the data that matches). the attribute table added the datafields to the attribute table from the excel spreadsheet but all of the data is blank!!   I have tried looking at the field "type" as ive read that it has been an issue before but it seems to be OK.  Is there anything anyone can suggest? It is possible to migrate a question from one Stack Exchange site to another by closing, but if I have a question that I think is on-topic for multiple Stack Exchange sites, is it OK to post it on both (multipost)?   For example, I have a question that's earned me the tumbleweed badge on SO and I'm not sure what the best thing to do with it is. It's about a web server so it might be answerable on Server Fault but it's really more of a programming thing, hence the posting the question on Stack Overflow.    Is there any way to make the question visible on multiple sites (crosspost) and then accept the answer wherever it came from? Area 51 layout breaks when zoomed to 90% Having recently introduced an overload of a method the application started to fail. Finally tracking it down, the new method is being called where I did not expect it to be.  We had  setValue( const std::wstring&amp; name, const std::wstring&amp; value );  std::wstring avalue( func() ); setValue( L"string", avalue ); std::wstring bvalue( func2() ? L"true", L"false" ); setValue( L"bool", bvalue ); setValue( L"empty", L"" );   It was changed so that when a bool value is stored we use the same strings (internal data storage of strings)  setValue( const std::wstring&amp; name, const std::wstring&amp; value ); setValue( const std::wstring&amp; name, const bool&amp; value );  std::wstring avalue( func() ); setValue( L"string", avalue ); setValue( L"bool", func2() ); setValue( L"empty", L"" ); &lt;&lt; --- this FAILS!?!   The problem with L"" is that it is implicitly casting and previously it was happy to be a std::wstring, but not it prefers to be a bool. The MSVC compiler does not complain, or raise warning, so I'm worried that even if I "fix" the setValue( L"empty", L"" ); to be  setValue( L"empty", std::wstring() );   somebody else may come later and simply use setValue( L"empty", L"" ); and have to track down this issue again.  We thought to use explicit on the method but it is not a valid keyword for this usage. Is there some way to get the compiler to complain about this, or otherwise prevent the issue?  Otherwise I'm thinking to change the name of the method which takes a bool to ensure it can't make an incorrect guess. Syntax highlighting with less, trouble with lexer I have installed python-pygments and using it for syntax highlighting with less as described by mankoff  I put a function in my .bashrc  cless () {     pygmentize -f terminal "$1" | less -R }   it is enabling syntax highlighting with less. But when I am going to open a file like /etc/fstab or /etc/apt/apt.conf a error saying  Error: no lexer for filename '/etc/apt/apt.conf' found   I found option to show pygmentize the lexer with -l at this . But what will be the appropriate lexer for such files? and how to use it? For wall-sized graphics and large banners (e.g. 3m × 5m), what is an acceptable PPI for print? As I understand it 300 ppi is the typical for 'small' artworks (esp. for clean text resolution). However, for small artworks, the audience usually engages at a much closer distance. Therefore, in the interests of keeping a bitmap file down to a reasonable size, can you get away with a much-reduced PPI for a large format/banner print? Change \textwidth and \textheight in mid-document "Firstly" or "first"? I am trying to INSERT INTO a table using the input from another table. Although this is entirely feasible for many database engines, I always seem to struggle to remember the correct syntax for the SQL engine of the day (, , , , and ).  Is there a silver-bullet syntax coming from an SQL standard (for example, ) that would allow me to insert the values without worrying about the underlying database? How to show that for all k, $k! \ge (k/2)^{k/2}$ Finding a formula to sum natural numbers up to $n$ Possible Duplicate:          I got this question in homework:  Find an expression for the sum ‫‪     $\sum k = 1 +\cdots + n‬‬$.    and prove it using an induction.   I'm not even near finding the expression. What I did notice is that if $n$ is (for example) 5 then the sum would be   $5^2 - 4^2 + 3^2 - 2^2 + 1^2$  So the first number is always positive and from there on the sign changes.  Any tips on how do I contintue from this point on, assuming I'm in the right direction?  Thanks! Can graduated Stack Exchange sites get closed too? How can I download an APK file from the Play Store? Can the Dispel Magic spell be Readied to counter an opponent's spell? When playing as a spellcaster, is it valid the use of the Ready action to prepare Dispel Magic to counter a spell cast by an opponent? In the same vein, when declaring said action, do I have to specify which spell slot I will use when Readying the Dispel Magic spell? If that is the case, does this tactic nullify an opponent's spell? I get the impression that this is basically turning Dispel Magic into a spell with a casting time of &quot;1 reaction&quot;. Is my reading of the rules accurate? Is it possible to create a geocoding and reverse geocoding service based on the shapefiles data Xubuntu 18.04 Persistent Live USB: Will persistence be carried upon full installation to a machine? I've created an Xubuntu 18.04 persistent live USB stick and installed several softwares for web development, such as XAMPP, Sublime Text 3, Google Chrome, etc.. I did some configurations as well in the ~/.bashrc file.  I am wondering if these installation and configuration in my persistent live USB stick be carried over in a full installation in to a new machine using it. CSS two divs next to each other I want to put two &lt;div&gt;s next to each other. The right &lt;div&gt; is about 200px; and the left &lt;div&gt; must fill up the rest of the screen width? How can I do this? Is any divergence-free curl-free vector field necessarily constant?