Are we accepting questions which will only help OP and not future visitors?
Responding to your "too localized" concerns
apex:inputField can only be used with sObjects I am trying to create a custom visualforce page that saves new opportunity contact roles to an opportunity. I am having trouble creating the first step of listing out all contacts that relate to that account. The error I am getting is...     Save error: Could not resolve the entity from  value binding '{!u.contact}'.   can only be used with SObjects, or objects that are Visualforce field component resolvable.   I do not understand why I am receiving this error. u.contact should resolve to a Contact object, which is an sObject. Am I misunderstanding something?  Here is my code...  Controller  public class ChooseContactController  {     public String accountId = ApexPages.currentPage().getParameters().get('accountId');     public Account account { get; set; }     public List&lt;UnfundedOpportunityContactRole&gt; unfundedOpportunityContactRoles { get; set; }      public ChooseContactController()      {          unfundedOpportunityContactRoles = new List&lt;UnfundedOpportunityContactRole&gt;();         List&lt;Contact&gt; contacts = [SELECT Id, Name FROM Contact WHERE AccountId =: accountId];         account = [SELECT Id, Name FROM Account WHERE Id =: accountId];          for(Contact c: contacts)          {             unfundedOpportunityContactRoles.add(new UnfundedOpportunityContactRole(c, 'The Man'));         }     }      public void Save() {}     public void Create() {}      public class UnfundedOpportunityContactRole     {         public Contact contact { get; set; }         public String role { get; set; }          public UnfundedOpportunityContactRole() { }          public UnfundedOpportunityContactRole(Contact contactParam, String roleParam)         {             this.contact = contactParam;             this.role = roleParam;         }     } }   VF page  &lt;apex:page controller="ChooseContactController"&gt;   &lt;apex:form &gt;     &lt;apex:pageBlock title="Choose a contact" mode="edit"&gt;       &lt;apex:pageBlockButtons &gt;         &lt;apex:commandButton action="{!create}" value="New"/&gt;         &lt;apex:commandButton action="{!save}" value="Save"/&gt;       &lt;/apex:pageBlockButtons&gt;         &lt;apex:pageBlockSection title="{!account.Name}"&gt;           &lt;apex:dataTable value="{!unfundedOpportunityContactRoles}" var="u"&gt;             &lt;apex:column headerValue="Contact"&gt;               &lt;apex:inputField value="{!u.contact}" /&gt;             &lt;/apex:column&gt;             &lt;apex:column headerValue="Role"&gt;               &lt;apex:inputField value="{!u.role}" /&gt;             &lt;/apex:column&gt;           &lt;/apex:dataTable&gt;         &lt;/apex:pageBlockSection&gt;     &lt;/apex:pageBlock&gt;   &lt;/apex:form&gt; &lt;/apex:page&gt; Navier-Stokes system I just bought a new house and I'm looking to run some cables. One of the areas I would like to run it to would require drilling through a 2x10 sistered joist. Realizing that going through the joist should be a last resort, if the hole is 1/4" and in the middle of one of the joists will this weaken the integrity?  I have seen lots of articles about drilling through the depth of a joist, but very few regarding drilling vertically. Correct usage of "see" vs. "watch" Importing users that will be installed by programs Should the bias value be added after convolution operation in CNNs? Any Info on Generalized Binomial and Exponential Series? I was reading Concrete Mathematics by Knuth et al. and on p. 200, it references the generalized binomial series $\mathcal B_t(z)$ and the generalized exponential series $\mathcal E_t(z)$, defined as $$\mathcal B_t(z)=\sum_{k\ge0}(tk)^{\underline{k-1}}\frac{z^k}{k!}\quad\text{and}\quad\mathcal E_t(z)=\sum_{k\ge0}(tk+1)^{k-1}\frac{z^k}{k!},$$ where $x^{\underline k}$ denotes the falling factorial. I was interested in the generalized binomial series because it satisfied the identity $$\frac{\mathcal B_t(z)^r}{1-t+t\mathcal B_t(z)^{-1}}=\sum_{k\ge0}\binom{tk+r}{k}z^k.$$ I've been trying to find a way to compute the sum $\sum_{n\le k\le m}\binom{tk+r}{k}$, so this seemed related. It seems that $\mathcal E_1(z)$ is also somewhat related to the Lambert $W$ function, though I might be wrong. Searching them up online didn't seem to get anywhere, and I just want to find more sources where I can learn about these functions. If anyone can find some resources, I'd appreciate it! What are the differences between $$, \[, align, equation and displaymath? For which values of $\alpha$ and $\beta$ does the integral $\int\limits_2^{\infty}\frac{dx}{x^{\alpha}\ln^{\beta}x}$ converge? Definition of $\mathbb{R}^\infty$ Question: Why is the topological space $\mathbb{R}^\infty$ defined to be the subset of $\prod_{i=1}^\infty \mathbb{R}_i$ consisting of sequences $(a_i)_{i=1} ^{\infty}$ such at most finitely many $a_i\neq 0$? Why does one insist on the condition that $a_i\neq0$ for at most finitely many $i$? Can I still use a usb flash drive after spilling water on it? So a few months ago I accidentally spilled a little water on a few of my usb flash drives. I really want to test and see if they work, but before I do, I just want to make sure that there's no risk of damaging my computer. I'm pretty sure it's fine, but I just got a new laptop and would hate to ruin it over something stupid. No connection could be made because the target machine actively refused it (PHP / WAMP) Bounds on off-diagonal entries of a correlation matrix Finding what methods a Python object has Given a Python object of any kind, is there an easy way to get the list of all methods that this object has?  Or,  if this is not possible, is there at least an easy way to check if it has a particular method other than simply checking if an error occurs when the method is called? Splitting all lines in layer at vertices using QGIS What is the relationship between philosophy and science? While philosophy and science as held as separate disciplines (and often taught in completely different colleges within a university [i.e. College of Liberal Arts vs. College of Science]), it is patently clear that there is an immutable relationship between philosophy and science. Philosophy can often be seen as providing justification for particular scientific theories -- but why/how is this so?  In science:   A theory must have observable consequences that can be tested and be falsified.   Theories also must agree with previous theories in the domains where they had been successfully tested.   For example,  special relativity reduces to Newton mechanics in the domain of velocities much less than the speed of light.  In philosophy, while new theories must comply with existing theories, there is clearly much less testing/retesting.  So, how does philosophy fit into this framework while maintaining the rigor required for scientific inquiry?  Are there any examples of philosophical discussions that have significantly influenced or changed scientific theory? The general advise is that you should not call GC.Collect from your code, but what are the exceptions to this rule?  I can only think of a few very specific cases where it may make sense to force a garbage collection.   One example that springs to mind is a service, that wakes up at intervals, performs some task, and then sleeps for a long time. In this case, it may be a good idea to force a collect to prevent the soon-to-be-idle process from holding on to more memory than needed.   Are there any other cases where it is acceptable to call GC.Collect? MySQL Error 1093 - Can't specify target table for update in FROM clause I have a table story_category in my database with corrupt entries. The next query returns the corrupt entries:  SELECT *  FROM  story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category INNER JOIN         story_category ON category_id=category.id);   I tried to delete them executing:  DELETE FROM story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category        INNER JOIN story_category ON category_id=category.id);   But I get the next error:      #1093 - You can't specify target table 'story_category' for update in FROM clause    How can I overcome this? How to monitor USB power consumption? I'm looking for a way to monitor the power being drawn from the USB ports on my Mac.  System Profiler doesn't appear to display this and I haven't been able to find any applications or tools to do the job either.  Can anyone suggest anything (preferably software based)? 2D and 3D vectors in Tikz I would like to draw some 2D and 3D vectors in Tikz with certain properties. The following primitive graph sums what I desire:   I just need the first quadrant of the Cartesian coordinate system for my representation.  I need the vector to be connected to the respective values on the distinct dimensions(not a projection, just orthogonal dashed lines).   The code segment below does what I want to achieve in 3D with two exceptions:  The projections on the xy plane and z dimension are given instead of connecting the head of the vector to the corresponding value in each dimension.  Numerical values are missing in dimensions.   Code: \documentclass[tikz]{standalone} \usepackage{tikz-3dplot} \begin{document}  \tdplotsetmaincoords{60}{120} \begin{tikzpicture}     [scale=3,     tdplot_main_coords,     axis/.style={-&gt;,blue,thick},     vector/.style={-stealth,red,very thick},     vector guide/.style={dashed,red,thick}]  %standard tikz coordinate definition using x, y, z coords \coordinate (O) at (0,0,0);  %tikz-3dplot coordinate definition using r, theta, phi coords \tdplotsetcoord{P}{.8}{55}{60}  %draw axes \draw[axis] (0,0,0) -- (1,0,0) node[anchor=north east]{$x$};     \draw[axis] (0,0,0) -- (0,1,0) node[anchor=north west]{$y$};     \draw[axis] (0,0,0) -- (0,0,1) node[anchor=south]{$z$};  %draw a vector from O to P \draw[vector] (O) -- (P);  %draw guide lines to components \draw[vector guide] (O) -- (Pxy); \draw[vector guide] (Pxy) -- (P); \end{tikzpicture} \end{document}