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mysqli_fetch_assoc() expects parameter / Call to a member function bind_param() errors. How to get the actual mysql error and fix it?
How can I stop the symbolic x coords to be plotted twice? I have created a bar diagram similar to:   But at a certain width the symbolic x coords are plotted twice. How can I manage the x axis correctly?  Here is my mini example:  \documentclass[12pt,a4paper,]{scrartcl} \usepackage{a4wide} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[ngerman]{babel} \usepackage{graphicx} \usepackage{tikz} \usepackage[miktex]{gnuplottex}  \usepackage{pgfplots}    \begin{document}     \begin{figure}         \begin{tikzpicture}         \begin{axis}[%         width=1\linewidth,         height=0.5\linewidth,         axis x line=center,         axis y line=left,         symbolic x coords={CP-Schelle,Mistel-Schelle V2,Mistel-Schelle V4,Mistel-Schelle V4.2D,Gewickelt nach Inspire},         enlargelimits=true,         ymin=0,         nodes near coords,         x tick label style={         font=\small,         text width=1cm,         align=center         },         ybar]         \addplot[color=gray, fill] coordinates {(CP-Schelle,1.000)};         \addplot[color=blue, fill] coordinates {(Mistel-Schelle V2,2.459)(Mistel-Schelle V4,3.318)(Mistel-Schelle V4.2D,2.243)(Gewickelt nach Inspire,1.782)};         \end{axis}         \end{tikzpicture}     \end{figure}      \begin{figure}         \begin{tikzpicture}         \begin{axis}[%         width=0.6\linewidth,         height=0.5\linewidth,         axis x line=center,         axis y line=left,         symbolic x coords={CP-Schelle,Mistel-Schelle V2,Mistel-Schelle V4,Mistel-Schelle V4.2D,Gewickelt nach Inspire},         enlargelimits=true,         ymin=0,         nodes near coords,         x tick label style={             font=\small,             text width=1cm,             align=center         },         ybar]         \addplot[color=gray, fill] coordinates {(CP-Schelle,1.000)};         \addplot[color=blue, fill] coordinates {(Mistel-Schelle V2,2.459)(Mistel-Schelle V4,3.318)(Mistel-Schelle V4.2D,2.243)(Gewickelt nach Inspire,1.782)};         \end{axis}         \end{tikzpicture}     \end{figure}  \end{document} QGIS3 - Clipping polygons to a hemisphere for azimuthal orthographic projection I'm a bit of a novice with QGIS, so this is really throwing me for a loop.  For the maps I'm intending on making, an azimuthal orthographic projection would be my preference.   For example, one map I'm trying to recreate is this map of the Pacific islands :    I've been using the NaturalEarth Quick Start package, which has been a really good launching-off point, but I'm running into some issues at the horizon of the orthographic projection.  I've tried adding a custom projection:  +proj=ortho +lat_0=0 +lon_0=170 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs   But that gives the following map:    Which certainly is close to being right, but the ocean is obviously being cut off in the Arctic and on the southern horizon.  I understand the issue is that naively mapping layers described in WGS 84 to an orthographic projection leaves you with artifacts at the horizon, but how do I fix it?    I first tried to use the Clip to Hemisphere plugin described in , but it seems incompatible with QGIS 3; when I try adding the plugin, QGIS3 gives an error message and places it in the "Invalid" section of the Plugins window.    I then tried both solutions presented at  Again the issue is with QGIS 2/3 incompatibility.    For Solution 1, both Numerical Digitize and CAD Tools are again incompatible with QGIS 3 and give the same result as Clip to Hemisphere.    For Solution 2, I can't disable on-the-fly-reprojection in settings since that setting was removed in QGIS 3. Is it advisable to use lead-free PCB and solder paste on a first SMD assembly job? Chromatic polynomial properties I have some properties which I do not understand how to form a proof for. Most of them are by induction, which is not my strong point Any help would be fantastic.   Looking at the chromatic polynomial $$P_G(k)=P_{G-e}(k) - P_{G/e}(k)$$  Properties   1.If G has n  vertices then $ P_g(k)$ has degree n and the coefficient of $k^n $ is 1   The signs of $P_g(k) $ alternate If G has q components the smalles non-zero term of $P_g(k)$ is the term in $k^q$ Is there a way to save composite node presets? Is there any way in Blender to save settings in your compositing node setup. For example say for my shadow catcher I have it setup for a hard shadow for sunlight, and then I also have a setting for diffuse light shadow for indoors. Is there any way I can save these settings individually so I can quickly switch to them rather than having to individually change the nodes every time. How to get vertex normals from a shape-key in Python? I'm trying to create an exporter for a format, which includes shape key support. This format requires both vertex coordinates and normals to be specified. This should be logical, because the vertex selected on the image below won't have the same normals:     Comparing it to this one:    But I actually haven't found any way to export shape key normals. Both Bmesh Vertex and ShapeKey Vertex only store the coordinates.  Is there any way to get them? Where can I find sugar cane? I played several hours a started three different worlds in Minecraft, but I have never found any sugar canes. I read on Minecraft wiki to search near water but still no luck. Do you have more hints? Is it possible to re-create an environment that allow sugar canes to naturally grow? how disable resume hard disk from Sleep on Shut Down I'm using Windows 7 , I set my drive to sleep after 10 minutes and it works but, when I shut down windows my hard drive resume from sleep. Why? It shouldn't keep hard drive sleep and shut down the PC ? What documents to show if I'm a US citizen with no US passport to re-enter the US? Suppose I am a naturalized citizen of the US, but also a citizen of another country, "XYZ". I then boarded a plane and left the US to another country (maybe not necessarily to XYZ), without first getting a US passport, but using my old, but valid XYZ passport.   In this case what would be the best documents to have for me to gain entry back into the US as a US Citizen without a passport?  Would I need to contact the US Embassy for help in order to be able return?  If the airline does let me aboard to return to the US, even without the US passport, what are the best documents could I show at the border to prove I am a US citizen but that I just don't have a passport, for whatever reason? Prerequisites for AIC model comparison What are exactly the prerequisites, that need to be fulfilled for AIC model comparison to work?  I just came around this question when I did comparison like this:  &gt; uu0 = lm(log(usili) ~ rok) &gt; uu1 = lm(usili ~ rok) &gt; AIC(uu0) [1] 3192.14 &gt; AIC(uu1) [1] 14277.29   This way I justified the log transformation of variable usili. But I don't know if I can AIC-compare models when for example the dependent variable is different?  Ideal answer would include the list of prerequisites (mathematical assumptions). AMD GPU Material in "material preview mode" and "rendered mode", is entirely gray as background. Only outline is displayed I don't know why but now, when i go in material preview or rendered (in solid mode it works fine), my object is entirely gray, or invisible idk, because it has the same color of the background. I've been working for days on this project without having this issue, it suddenly showed up. I tried opening other old projects and suddenly they all do the same so i guess it is some blender program setting that applies for all the projects, but idk how it happened cuz i didn't change anything :/, anyone got any tips? I am wondering if there exists any formula for the following power series :  $$S = r + r^2 + r^4 + r^8 + r^{16} + r^{32} + ...... + r^{2^k}$$  Is there any way to calculate the sum of above series (if $k$ is given) ? How are the age restrictions followed by ICC for under 19 cricket tournaments? I have some doubts under this topic,   Can a player aged 19 play under 19 international cricket match? (Since 19 is not under 19) Consider a player having birthday during the series/tournament. How the age will be calculated for him? How do I bind a WPF DataGrid to a variable number of columns? My WPF application generates sets of data which may have a different number of columns each time.  Included in the output is a description of each column that will be used to apply formatting.  A simplified version of the output might be something like:  class Data {     IList&lt;ColumnDescription&gt; ColumnDescriptions { get; set; }     string[][] Rows { get; set; } }   This class is set as the DataContext on a WPF DataGrid but I actually create the columns programmatically:  for (int i = 0; i &lt; data.ColumnDescriptions.Count; i++) {     dataGrid.Columns.Add(new DataGridTextColumn     {         Header = data.ColumnDescriptions[i].Name,         Binding = new Binding(string.Format("[{0}]", i))     }); }   Is there any way to replace this code with data bindings in the XAML file instead? How to transfer a DVD to my hard drive Copy maintenance plans to a different server Is there a way to copy maintenance plans from one SQL Server 2012 to another? Both servers are not accessible via the same copy of Management Studio at the same time (on different networks). Why doesn't Volumetric follow the shape of Mesh in Eevee? So I was in the middle of making a ball-shaped smoke, but the volumetric effect didn't work following the basic shape. It remains cube in Eevee Blender 2.8; while in Cycle it works, but in Cycle it takes thousands of years for Render. Non-abelian group $G$ satisfying $(a \cdot b)^i=a^i \cdot b^i,$ for two consecutive integers. Given an example of a non-abelian group $G$ satisfying $(a \cdot b)^i=a^i \cdot b^i, \forall a, b \in G$ for two consecutive integers.   This is question 5 from Herstein Page 35. I have proved that conclusion holds for three positive integers.Thanks. What is a word for someone who is experienced and wise, but who deliberately acts naïve?    I don’t intend it for sarcastic use; I’m trying to describe someone succeeding in making people think that that person truly is naïve.   Is there a word for this? Secure hash and salt for PHP passwords It is currently said that MD5 is partially unsafe. Taking this into consideration, I'd like to know which mechanism to use for password protection.  This question,   suggests that hashing multiple times may be a good idea, whereas  suggests using salt.  I'm using PHP. I want a safe and fast password encryption system. Hashing a password a million times may be safer, but also slower. How to achieve a good balance between speed and safety? Also, I'd prefer the result to have a constant number of characters.   The hashing mechanism must be available in PHP It must be safe It can use salt (in this case, are all salts equally good? Is there any way to generate good salts?)   Also, should I store two fields in the database (one using MD5 and another one using SHA, for example)? Would it make it safer or unsafer?  In case I wasn't clear enough, I want to know which hashing function(s) to use and how to pick a good salt in order to have a safe and fast password protection mechanism.  Related questions that don't quite cover my question: