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  • How do I distinguish a SharePoint file update as being from a file upload?

    - by ccomet
    In SharePoint, when an item is first added to a document library, it fires the ItemAdded and ItemAdding events as expected. And if you upload the same filename to update the existing file, it will fire off ItemUpdated and ItemUpdating events, likewise as expected. However, I have been unsuccessful at determining whether this kind of action has actually occurred or not. Or, more specifically, I am entirely unable to differentiate between the following: An item is updated because someone uploaded a new file but did nothing to any of the form fields. An item is updated because someone hit "OK" but did nothing to any of the form fields. Is there actually a way to distinguish these kinds of updates? There appears to be nothing in event properties that contains this information, nor in the version history for both the list item and the file itself. I have even tried comparing the files themselves via OpenBinary(), but in both mentioned cases I still get the same result. Thank you in advance for any help!

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  • Extension methods for encapsulation and reusability

    - by tzaman
    In C++ programming, it's generally considered good practice to "prefer non-member non-friend functions" instead of instance methods. This has been recommended by Scott Meyers in this classic Dr. Dobbs article, and repeated by Herb Sutter and Andrei Alexandrescu in C++ Coding Standards (item 44); the general argument being that if a function can do its job solely by relying on the public interface exposed by the class, it actually increases encapsulation to have it be external. While this confuses the "packaging" of the class to some extent, the benefits are generally considered worth it. Now, ever since I've started programming in C#, I've had a feeling that here is the ultimate expression of the concept that they're trying to achieve with "non-member, non-friend functions that are part of a class interface". C# adds two crucial components to the mix - the first being interfaces, and the second extension methods: Interfaces allow a class to formally specify their public contract, the methods and properties that they're exposing to the world. Any other class can choose to implement the same interface and fulfill that same contract. Extension methods can be defined on an interface, providing any functionality that can be implemented via the interface to all implementers automatically. And best of all, because of the "instance syntax" sugar and IDE support, they can be called the same way as any other instance method, eliminating the cognitive overhead! So you get the encapsulation benefits of "non-member, non-friend" functions with the convenience of members. Seems like the best of both worlds to me; the .NET library itself providing a shining example in LINQ. However, everywhere I look I see people warning against extension method overuse; even the MSDN page itself states: In general, we recommend that you implement extension methods sparingly and only when you have to. So what's the verdict? Are extension methods the acme of encapsulation and code reuse, or am I just deluding myself?

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  • Password hashing, salt and storage of hashed values

    - by Jonathan Leffler
    Suppose you were at liberty to decide how hashed passwords were to be stored in a DBMS. Are there obvious weaknesses in a scheme like this one? To create the hash value stored in the DBMS, take: A value that is unique to the DBMS server instance as part of the salt, And the username as a second part of the salt, And create the concatenation of the salt with the actual password, And hash the whole string using the SHA-256 algorithm, And store the result in the DBMS. This would mean that anyone wanting to come up with a collision should have to do the work separately for each user name and each DBMS server instance separately. I'd plan to keep the actual hash mechanism somewhat flexible to allow for the use of the new NIST standard hash algorithm (SHA-3) that is still being worked on. The 'value that is unique to the DBMS server instance' need not be secret - though it wouldn't be divulged casually. The intention is to ensure that if someone uses the same password in different DBMS server instances, the recorded hashes would be different. Likewise, the user name would not be secret - just the password proper. Would there be any advantage to having the password first and the user name and 'unique value' second, or any other permutation of the three sources of data? Or what about interleaving the strings? Do I need to add (and record) a random salt value (per password) as well as the information above? (Advantage: the user can re-use a password and still, probably, get a different hash recorded in the database. Disadvantage: the salt has to be recorded. I suspect the advantage considerably outweighs the disadvantage.) There are quite a lot of related SO questions - this list is unlikely to be comprehensive: Encrypting/Hashing plain text passwords in database Secure hash and salt for PHP passwords The necessity of hiding the salt for a hash Clients-side MD5 hash with time salt Simple password encryption Salt generation and Open Source software I think that the answers to these questions support my algorithm (though if you simply use a random salt, then the 'unique value per server' and username components are less important).

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  • How can I make Excel's MIN function ignore zeroes in a set?

    - by mfg
    In Excel, I have the following formula =(MIN(H69,H52,H35,H18)*(1/H18))*10 that is supposed to return the MIN of a range, and divide it by the current cell (*(1/H18) ), then multiply by 10. I am having difficulty with adding a type of NULLIF statement. I want to be able to have (the possibility for) blank rows, and have the MIN function ignore zero/blank fields while selecting the next lowest value (all are between 1.0-0.1). Is there a modifier i can apply to the MIN function to make it not compare zeroes in the MIN set? Is there a better funtion than MIN to use? This is to prevent the following situation: users will need to eliminate fields that are zeros from the form, theres 2 formula edits per entry, averaging 4 entries per use, so 8 possible errors per form use...

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  • Django database caching

    - by hekevintran
    I have a Django form that uses an integer field to lookup a model object by its primary key. The form has a save() method that uses the model object referred to by the integer field. The model's manager's get() method is called twice, once in the clean method and once in the save() method: class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is the first call to get MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): id_a = self.cleaned_data['id_a'] # here is the second call to get my_model_object = MyModel.objects.get(id=id_a) # do other stuff I wasn't sure whether this hits the database two times or one time so I returned the object itself in the clean method so that I could avoid a second get() call. Does calling get() hit the database two times? Or is the object cached in the thread? class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is my workaround return MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): # looking up the cleaned value returns the model object my_model_object = self.cleaned_data['id_a'] # do other stuff

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  • Core Data - 'calculated' attributes

    - by nephilim
    I have two entities: A and B A has two properties from and to, both pointing to the B entity. B as a fetched property to A with predicate from == $FETCH_SOURCE or to = $FETCH_SOURCE -- (from) -> A -- (to) -> B <- (As) -- In my application I select a certain B instance, and then show all of its A instances. Now, in my table the columns are bound to an array controller containing the selected A instances. I want to 'merge' the from and to columns. I already know one of the columns will be equal to the selected B instance, so now I'm only interested in the second value. The options I see: create a custom class for the B entity and create a method that returns either value. It should somehow be able to retrieve which B instance is currently selected. create a custom DataSource. Most columns are still using bindings, so then we'd have to access the NSArrayController's array so we're sure we have the right object. create a custom DataSource, remove the NSArrayController and do all the Core Data stuff ourselves. Is there any 'right' way to solve this?

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  • Dynamics CRM 2013 rich text editor

    - by user2962918
    I am using Dynamics CRM 2013. How does one apply the rich text editor styling seen on the description field on the email form to other multiple line text fields? Viewing the source code it is obvious that the system is treating the rich text field very differently from the normal multiple line text fields in that instead of rendering a textarea it is rendering a table with an embedded iframe. In CRM 2011, I have used extensions that wrap up the TinyMCE editor but they were never very effective. It seems odd that I can't just check a box to do this to any text field in the settings when the behaviour is obviously built in. Thanks in advance. Richard.

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  • Associating an object with another object for GC clearup

    - by thecoop
    Is there any way of associating an object instance (object A) with a second object (object B) in a generalised way, so that when B gets collected A becomes eligable for collection? The same behaviour that would happen if B had an instance variable pointing to A, but without explicitly changing the class definition of B, and being able to do this in a dynamic way? The same sort of effect could be done by using the Component.Disposed event in a funky way, but I don't want to make B disposable EDIT I'm basically creating a cache of objects that are associated with a single 'root' object, and I don't want the cache to be static, as there can be lots of root objects using different caches, so lots of memory will be used up when a root object is no longer used but the cached objects are still around. So, I want a collection of cached objects to be associated with each 'root' object, without changing the root object definition. Sort of like metadata of an extra object reference attached to each root object instance. That way, each collection will get collected when the root object is collected, and not hang around like they would if a static cache was used.

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  • acts_as_solr returns all rows in the database when using the model as search query

    - by chris Chan
    In our application we're using acts_as_solr for search. Everything seems to be running smoothly except for the fact that using the model name as the search query returns every single row in the table. For example, let's say we have a users table. We specify acts_as_solr in our model to search the fields first name, last name and handle acts_as_solr :fields = [:handle, :lname, :fname]. When you use "user" as the search term it returns every single user in the system, or every row in the database as a result. Has anyone else run into this?

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  • Clearing input text feilds when clicked on in Flash (AS 2.0)

    - by rickstyphilis
    I have a problem where I want a text field that by default has the word NAME in it, to become empty when a user clicks on it. The text field has the instance name 'nam' and is inside a movie with the instance name 'input_text'. I've searched around and found samples of code where everyone keeps suggesting this: textboxinstancename.onSetFocus = function() { textboxinstancename.text = ""; }; should work. It seems to work for everyone else but me. I've tried using the following on the first frame of the 'input_text' movie with no luck: this.input_text.nam.onSetFocus = function() { this.input_text.nam.text = "" } I've tried putting this on the first frame of the scene, again with no result: _root.input_text.nam.onSetFocus = function() { _root.input_text.nam.text = "" } I've tried this in the same manner as the last respectively with both 'this' on the instance and '_root' on the scene (denoted by x): x.input_text.nam.onSetFocus = function() { if (x.input_text.nam.text == "NAME") { x.input_text.nam.text = ""; } }; Still no luck. Can anyone tell me what I might be doing wrong?

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  • PDO update query with conditional?

    - by dmontain
    I have a PDO mysql that updates 3 fields. $update = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2, field3=:field3 WHERE key=:key"); But I want field3 to be updated only when $update3 = true; (meaning that the update of field3 is controlled by a conditional statement) Is this possible to accomplish with a single query? I could do it with 2 queries where I update field1 and field2 then check the boolean and update field3 if needed in a separate query. //run this query to update only fields 1 and 2 $update_part1 = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2 WHERE key=:key"); //if field3 should be update, run a separate query to update it separately if ($update3){ $update_part2 = $mypdo->prepare("UPDATE tablename SET field3=:field3 WHERE key=:key"); } But hopefully there is a way to accomplish this in 1 query?

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  • Test if element already has jQuery datepicker

    - by macca1
    I have a form with many input elements. Some are date fields with a jQuery UI datepicker alraedy attached: $("#someElement").mask("9?9/99/9999").datepicker({showOn: 'button', buttonText:'Click here to show calendar', duration: 'fast', buttonImageOnly: true, buttonImage: /images/calicon.gif' }); Then I have a key command bound to this function: function openCalendar() { var selection = document.activeElement; // { Need to test here if datepicker has already been initialized $(selection).datepicker("show"); // } } This works great for elements which already have the datepicker on them. However any other fields will throw a javascript error. I'm wondering the best way to test to see if datepicker has already been initialized on that field.

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  • Getting the name of a child class in the parent class (static context)

    - by Benoit Myard
    Hi everybody, I'm building an ORM library with reuse and simplicity in mind; everything goes fine except that I got stuck by a stupid inheritance limitation. Please consider the code below: class BaseModel { /* * Return an instance of a Model from the database. */ static public function get (/* varargs */) { // 1. Notice we want an instance of User $class = get_class(parent); // value: bool(false) $class = get_class(self); // value: bool(false) $class = get_class(); // value: string(9) "BaseModel" $class = __CLASS__; // value: string(9) "BaseModel" // 2. Query the database with id $row = get_row_from_db_as_array(func_get_args()); // 3. Return the filled instance $obj = new $class(); $obj->data = $row; return $obj; } } class User extends BaseModel { protected $table = 'users'; protected $fields = array('id', 'name'); protected $primary_keys = array('id'); } class Section extends BaseModel { // [...] } $my_user = User::get(3); $my_user->name = 'Jean'; $other_user = User::get(24); $other_user->name = 'Paul'; $my_user->save(); $other_user->save(); $my_section = Section::get('apropos'); $my_section->delete(); Obviously, this is not the behavior I was expecting (although the actual behavior also makes sense).. So my question is if you guys know of a mean to get, in the parent class, the name of child class.

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  • Thoughts on GoGrid vs EC2

    - by Jason
    I am currently hosting my SaaS application at GoGrid (Microsoft stack). Here's what I have: Database Server - physical box, 12 GB RAM, 2 X Quad Core CPU (2.13 GHz Xeon E5506) 2 Web / App servers - cloud servers, 2 GB RAM, 2 VCPUs 300 GB monthly bandwidth I am paying around $900 / month for this. My web / app servers are busting at the seams and need to be upgraded to 4 GB of RAM. I also need a firewall, and GoGrid just added this service for an additional $200. After the upgrade, I will be paying around $1,400. I started looking at Amazon EC2, specifically this config: Database server - "High Memory Double Extra Large Instance" - 34 GB RAM, 13 EC2 compute units 2 Web / App servers - "Large Instance" - 7.5 GB RAM, 4 EC2 compute units If I go with 1 year reserved instances, my upfront cost would be $4,500 and my monthly would be $700. This comes to $1,075 / month when amortized. Amazon also includes a firewall for free. Here are my questions: Do any of you have experience running a database (especially SQL Server) on an EC2 instance? How did it perform compared to a dedicated machine? One of my major concerns is with disk I/O. Amazon's description of a compute unit is fairly vague. Any ideas on how the CPU performance on the database servers would compare? I am hoping that the Amazon solution will provide significantly better performance than my current or even improved GoGrid setup. Having a virtual database server would also be nice in terms of availability. Right now I would be in serious trouble if I had any hardware issues. Thanks for any insight...

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  • OOP - Handling Automated Instances of a Class - PHP

    - by dscher
    This is a topic that, as a beginner to PHP and programming, sort of perplexes me. I'm building a stockmarket website and want users to add their own stocks. I can clearly see the benefit of having each stock be a class instance with all the methods of a class. What I am stumped on is the best way to give that instance a name when I instantiate it. If I have: class Stock() { ....doing stuff..... } what is the best way to give my instances of it a name. Obviously I can write: $newStock = new Stock(); $newStock.getPrice(); or whatever, but if a user adds a stock via the app, where can the name of that instance come from? I guess that there is little harm in always creating a new child with $newStock = new Stock() and then storing that to the DB which leads me to my next question! What would be the best way to retrieve 20 user stocks(for example) into instances of class Stock()? Do I need to instantiate 20 new instances of class Stock() every time the user logs in or is there something I'm missing? I hope someone answers this and more important hope a bunch of people answer this and it somehow helps someone else who is having a hard time wrapping their head around what probably leads to a really elegant solution. Thanks guys!

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  • Perl, efficient parsing of csv file

    - by Mike
    I'm working on a project that involves parsing a large csv formatted file in Perl and am looking to make things more efficient. My approach has been to split() the file by lines first, and then split() each line again by commas to get the fields. But this suboptimal since at least two passes on the data are required. (once to split by lines, then once again for each line). This is a very large file, so cutting processing in half would be a significant improvement to the entire application. My question is, what is the most time efficient means of parsing a large CSV file using only built in tools? note: Each line has a varying number of tokens, so we can't just ignore lines and split by commas only. Also we can assume fields will contain only alphanumeric ascii data (no special characters or other tricks). Also, i don't want to get into parallel processing, although that might work effectively.

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  • Immutability of big objects

    - by Malax
    Hi StackOverflow! I have some big (more than 3 fields) Objects which can and should be immutable. Every time I run into that case i tend to create constructor abominations with long parameter lists. It doesn't feel right, is hard to use and readability suffers. It is even worse if the fields are some sort of collection type like lists. A simple addSibling(S s) would ease the object creation so much but renders the object mutable. What do you guys use in such cases? I'm on Scala and Java, but i think the problem is language agnostic as long as the language is object oriented. Solutions I can think of: "Constructor abominations with long parameter lists" The Builder Pattern Thanks for your input!

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  • What is the relation between ContentPane and JPanel?

    - by Roman
    I found one example in which buttons are added to panels (instances of JPanel) then panels are added to the the containers (instances generated by getContentPane) and then containers are, by the construction, included into the JFrame (the windows). I tried two things: I got rid of the containers. In more details, I added buttons to a panel (instance of JPanel) and then I added the panel to the windows (instance of JFrame). It worked fine. I got rid of the panels. In more details, I added buttons directly to the container and then I added the container to the window (instance of JFrame). So, I do not understand two things. Why do we have two competing mechanism to do the same things. What is the reason to use containers in combination with the panels (JPanel)? (For example, what for we include buttons in JPanels and then we include JPanels in the Containers). Can we include JPanel in JPanel? Can we include a container in container?

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  • How to call different methods from single webservices class

    - by pointer
    I have a following RESTful webservice, I have two methods for http get. One function signs in and other function signs out a user from an application. Following is the code: import javax.ws.rs.core.Context; import javax.ws.rs.core.UriInfo; import javax.ws.rs.PathParam; import javax.ws.rs.Consumes; import javax.ws.rs.PUT; import javax.ws.rs.Path; import javax.ws.rs.GET; import javax.ws.rs.POST; import javax.ws.rs.Produces; import javax.ws.rs.QueryParam; /** * REST Web Service * * @author Pointer */ @Path("generic") public class GenericResource { @Context private UriInfo context; /** * Creates a new instance of GenericResource */ public GenericResource() { } /** * Retrieves representation of an instance of * com.ef.apps.xmpp.ws.GenericResource * * @return an instance of java.lang.String */ @GET @Produces("text/html") public String SignIn(@QueryParam("username") String username, @QueryParam("password") String password, @QueryParam("extension") String extension) { //TODO return proper representation object return "Credentials " + username + " : " + password + " : " + extension; } @GET @Produces("text/html") public String SignOut(@QueryParam("username") String username, @QueryParam("password") String password, @QueryParam("extension") String extension) { //TODO return proper representation object return "Credentials " + username + " : " + password + " : " + extension; } } Now, where would I specify that which function I want to call for http get?

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  • PHP, MySQL, jQuery, AJAX: json data returns correct response but frontend returns error

    - by Devner
    Hi all, I have a user registration form. I am doing server side validation on the fly via AJAX. The quick summary of my problem is that upon validating 2 fields, I get error for the second field validation. If I comment first field, then the 2nd field does not show any error. It has this weird behavior. More details below: The HTML, JS and Php code are below: HTML FORM: <form id="SignupForm" action=""> <fieldset> <legend>Free Signup</legend> <label for="username">Username</label> <input name="username" type="text" id="username" /><span id="status_username"></span><br /> <label for="email">Email</label> <input name="email" type="text" id="email" /><span id="status_email"></span><br /> <label for="confirm_email">Confirm Email</label> <input name="confirm_email" type="text" id="confirm_email" /><span id="status_confirm_email"></span><br /> </fieldset> <p> <input id="sbt" type="button" value="Submit form" /> </p> </form> JS: <script type="text/javascript"> $(document).ready(function() { $("#email").blur(function() { var email = $("#email").val(); var msgbox2 = $("#status_email"); if(email.length > 3) { $.ajax({ type: 'POST', url: 'check_ajax2.php', data: "email="+ email, dataType: 'json', cache: false, success: function(data) { if(data.success == 'y') { alert('Available'); } else { alert('Not Available'); } } }); } return false; }); $("#confirm_email").blur(function() { var confirm_email = $("#confirm_email").val(); var email = $("#email").val(); var msgbox3 = $("#status_confirm_email"); if(confirm_email.length > 3) { $.ajax({ type: 'POST', url: 'check_ajax2.php', data: 'confirm_email='+ confirm_email + '&email=' + email, dataType: 'json', cache: false, success: function(data) { if(data.success == 'y') { alert('Available'); } else { alert('Not Available'); } } , error: function (data) { alert('Some error'); } }); } return false; }); }); </script> PHP code: <?php //check_ajax2.php if(isset($_POST['email'])) { $email = $_POST['email']; $res = mysql_query("SELECT uid FROM members WHERE email = '$email' "); $i_exists = mysql_num_rows($res); if( 0 == $i_exists ) { $success = 'y'; $msg_email = 'Email available'; } else { $success = 'n'; $msg_email = 'Email is already in use.</font>'; } print json_encode(array('success' => $success, 'msg_email' => $msg_email)); } if(isset($_POST['confirm_email'])) { $confirm_email = $_POST['confirm_email']; $email = ( isset($_POST['email']) && trim($_POST['email']) != '' ? $_POST['email'] : '' ); $res = mysql_query("SELECT uid FROM members WHERE email = '$confirm_email' "); $i_exists = mysql_num_rows($res); if( 0 == $i_exists ) { if( isset($email) && isset($confirm_email) && $email == $confirm_email ) { $success = 'y'; $msg_confirm_email = 'Email available and match'; } else { $success = 'n'; $msg_confirm_email = 'Email and Confirm Email do NOT match.'; } } else { $success = 'n'; $msg_confirm_email = 'Email already exists.'; } print json_encode(array('success' => $success, 'msg_confirm_email' => $msg_confirm_email)); } ?> THE PROBLEM: As long as I am validating the $_POST['email'] as well as $_POST['confirm_email'] in the check_ajax2.php file, the validation for confirm_email field always returns an error. With my limited knowledge of Firebug, however, I did find out that the following were the responses when I entered email and confirm_email in the fields: RESPONSE 1: {"success":"y","msg_email":"Email available"} RESPONSE 2: {"success":"y","msg_email":"Email available"}{"success":"n","msg_confirm_email":"Email and Confirm Email do NOT match."} Although the RESPONSE 2 shows that we are receiving the correct message via msg_confirm_email, in the front end, the alert 'Some error' is popping up (I have enabled the alert for debugging). I have spent 48 hours trying to change every part of the code wherever possible, but with only little success. What is weird about this is that if I comment the validation for $_POST['email'] field completely, then the validation for $_POST['confirm_email'] field is displaying correctly without any errors. If I enable it back, it is validating email field correctly, but when it reaches the point of validating confirm_email field, it is again showing me the error. I have also tried renaming success variable in check_ajax2.php page to other different names for both $_POST['email'] and $_POST['confirm_email'] but no success. I will be adding more fields in the form and validating within the check_ajax2.php page. So I am not planning on using different ajax pages for validating each of those fields (and I don't think it's smart to do it that way). I am not a jquery or AJAX guru, so all help in resolving this issue is highly appreciated. Thank you in advance.

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  • facebook graph api don´t publish to news feed

    - by rizidoro
    hi, im trying to update my news feed on facebook. Im using the new graph api. I can connect to graph, but when i try to publish some content to the feed object, nothing happens. here´s my code: <?php $token = "xxxx"; $fields = "message=test&access_token=$token"; $c = curl_init("http://graph.facebook.com/me/feed"); curl_setopt($c,"CURLOPT_POST", true); curl_setopt($c,"CURLOPT_POSTFIELDS",$fields); $r = curl_exec($c); print_r($r); this returns: {"error":{"type":"QueryParseException","message":"An active access token must be used to query information about the current user."}}1 then I try to pass access_token via GET: $c = curl_init("http://graph.facebook.com/me/feed?access_token=$token"); this returns: {"data":[]}1 Am I doing something wrong? thanks

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  • Changing a datatype solely for the purpose of Excel Export in Crystal Reports

    - by yeahumok
    I have a report that has several numerical fields. To fill a project requirement, i had to use the following formula: if {DataTable1.No of Investments}>9999 then '*****' else toText({DataTable1.No of Investments},0) Basically, if the number fed in is bigger than 9999 it turns into * on the report. Now, when i try to export into excel, not only is the data type for all fields, strings...but the * show up versus numbers. I was wondering if there was a way to re-cast this back into a numerical value SOLELY for the purpose of excel exportation so that i'd be able to use excel formulas as well as see numbers instead of asterisks. I'd only be doing data-only excel exports. Any ideas?

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  • Why does this extension method throw a NullReferenceException in VB.NET?

    - by Dan
    From previous experience I had been under the impression that it's perfectly legal (though perhaps not advisable) to call extension methods on a null instance. So in C#, this code compiles and runs: // code in static class static bool IsNull(this object obj) { return obj == null; } // code elsewhere object x = null; bool exists = !x.IsNull(); However, I was just putting together a little suite of example code for the other members of my development team (we just upgraded to .NET 3.5 and I've been assigned the task of getting the team up to speed on some of the new features available to us), and I wrote what I thought was the VB.NET equivalent of the above code, only to discover that it actually throws a NullReferenceException. The code I wrote was this: ' code in module ' <Extension()> _ Function IsNull(ByVal obj As Object) As Boolean Return obj Is Nothing End Function ' code elsewhere ' Dim exampleObject As Object = Nothing Dim exists As Boolean = Not exampleObject.IsNull() The debugger stops right there, as if I'd called an instance method. Am I doing something wrong (e.g., is there some subtle difference in the way I defined the extension method between C# and VB.NET)? Is it actually not legal to call an extension method on a null instance in VB.NET, though it's legal in C#? (I would have thought this was a .NET thing as opposed to a language-specific thing, but perhaps I was wrong.) Can anybody explain this one to me?

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  • MySQL indexes: how do they work?

    - by bob-the-destroyer
    I'm a complete newbie with MySQL indexes. I have several MyISAM tables on MySQL 5.0x having utf8 charsets and collations with 100k+ records each. The primary keys are generally integer. Many columns on each table may have duplicate values. I need to quickly count, sum, average, or otherwise perform custom calculations on any number of fields in each table or joined on any number of others. I found this page giving an overview of MySQL index usage: http://dev.mysql.com/doc/refman/5.0/en/mysql-indexes.html, but I'm still not sure I'm using indexes right. Just when I think I've made the perfect index out of a collection of fields I want to calculate against, I get the "index must be under 1000 bytes" error. Can anyone explain how to most efficiently create and use indexes to speed up queries? Caveat: upgrading Mysql is not possible in this case. Using Navicat Light for db administration, but this app isn't required.

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