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  • Using SET NULL and SET DEFAULT with Foreign Key Constraints

    Cascading Updates and Deletes, introduced with SQL Server 2000, were such an important, crucial feature that it is hard to imagine providing referential integrity without them. One of the new features in SQL Server 2005 that hasn't gotten a lot of press from what I've read is the new options for the ON DELETE and ON UPDATE clauses: SET NULL and SET DEFAULT. Let's take a look!

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  • Null Or Empty Coalescing

    - by Latest Microsoft Blogs
    In my last blog post, I wrote about the proper way to check for empty enumerations and proposed an IsNullOrEmpty method for collections which sparked a lot of discussion. This post covers a similar issue, but from a different angle. A very long time ago Read More......(read more)

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  • Could not connect to any LDAP server as (null) error

    - by wirelessman
    I am using a Windows 2008 Server as my LDAP server and on a Ubuntu 12.04 client I am trying to connect to it. I get the following error: nss_ldap: could not connect to any LDAP server as (null) - Can't contact LDAP server From my Ubuntu client I run the following: ldapsearch -h 10.1.1.251 -D admin -w password -s base dc=ad,dc=xxx,dc=com -p 389 and get the following success message # search result search: 2 result: 0 Success Any help would be greatly appreciated.

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  • Android - Force Close - Null Pointer on Canvas?

    - by user22241
    Please bear with me. I have a very odd problem. Basically, my app so far, has 3 activities (a main splash screen, an 'options/menu' screen and the main app). If I follow the very specific steps oulined below, I get a 'null pointer exception' in the 2nd activity) and the app force closes...... Here are the steps: Start the app (a game based on Surfaceview), tap through to the third activity so the game is running, then hit the home key so the game is paused and put to the background, the activity/app is ended through DDMS in the SDK then restarted on the device (all OK so far), now if I hit the back key on the device twice in quick succession, it happens. All other sequence of events is fine, even to the point of pressing the back key, waiting for the previous activity to show, then hitting back again - all OK. Only when the back key is pressed twice in quick succession following all the above steps does the problem occur. I'm assuming that the canvas isn't ready as it's showing as 'null' when this happens, but I'm not sure why this is happening as surely it's happening when I'm trying to go back to activity 1, but the logcat shows the error in activity 2. if I stop the activity running my 'doDraw' method (which referenced the canvas), then all is OK - so I can safely assume it is the canvas causing the problem. Also, if I skip my first activity (which is a very basic full-screen button which just displays a splashscreen and waits for the user to tap the screen), and make my 2nd activity the launch activity, again, it is OK. this is the part of the code that I think is probably relevant: @Override public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) { vheight = this.getHeight(); vwidth = this.getWidth(); } @Override public void surfaceCreated(SurfaceHolder holder) { vheight = this.getHeight(); vwidth = this.getWidth(); this.viewWidth = vwidth; this.viewHeight = vheight; if (runthread==false){ if (preThread.getState()==Thread.State.TERMINATED){ preThread = new OptionsThread(thisholder, thiscontext, thishandler); } preThread.setRunning(true); preThread.start();} } @Override public void surfaceDestroyed(SurfaceHolder holder) { preThread.setRunning(false); //Stop the loop boolean retry = true; //Stop the thread while (retry) { try { preThread.join(); retry = false; } catch (InterruptedException e) { } } Thank you all for any help you can offer

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  • Extension methods on a null object instance – something you did not know

    - by nmarun
    Extension methods gave developers with a lot of bandwidth to do interesting (read ‘cool’) things. But there are a couple of things that we need to be aware of while using these extension methods. I have a StringUtil class that defines two extension methods: 1: public static class StringUtils 2: { 3: public static string Left( this string arg, int leftCharCount) 4: { 5: if (arg == null ) 6: { 7: throw new ArgumentNullException( "arg" ); 8: } 9: return arg.Substring(0, leftCharCount); 10...(read more)

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  • SQL WHERE clause not returning rows when field has NULL value

    - by JohnB
    Ok, so I'm aware of this issue: When SET ANSI_NULLS is ON, all comparisons against a null value evaluate to UNKNOWN SQL And NULL Values in where clause SQL Server return Rows that are not equal < to a value and NULL However, I am trying to query a DataTable. I could add to my query: OR col_1 IS NULL OR col_2 IS NULL for every column, but my table has 47 columns, and I'm building dynamic SQL (string concatenation), and it just seems like a pain to do that. Is there another solution? I was to bring back all the rows that have NULL values in the WHERE comparison. UPDATE Example of query that gave me problems: string query = col_1 not in ('Dorothy', 'Blanche') and col_2 not in ('Zborna', 'Devereaux') grid.DataContext = dataTable.Select(query).CopyToDataTable(); (didn't retrieve rows if/when col_1 = null and/or col_2 = null)

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  • C++ std::vector problems

    - by Faur Ioan-Aurel
    For 2 days i tried to explain myself some of the things that are happening in my c++ code,and i can't get a good explanation.I must say that i'm more a java programmer.Long time i used quite a bit the C language but i guess Java erased those skills and now i'm hitting a wall trying to port a few classes from java to c++. So let's say that we have this 2 classes: class ForwardNetwork { protected: ForwardLayer* inputLayer; ForwardLayer* outputLayer; vector<ForwardLayer* > layers; public: void ForwardNetwork::getLayers(std::vector< ForwardLayer* >& result ) { for(int i= 0 ;i< layers.size(); i++){ ForwardLayer* lay = dynamic_cast<ForwardLayer*>(this->layers.at(i)); if(lay != NULL) result.push_back(lay); else cout << "Layer at#" << i << " is null" << endl; } } void ForwardNetwork::addLayer ( ForwardLayer* layer ) { if(layer != NULL) cout << "Before push layer is not null" << endl; //setup the forward and back pointer if ( this->outputLayer != NULL ) { layer->setPrevious ( this->outputLayer ); this->outputLayer->setNext ( layer ); } //update the input layer and outputLayer variables if ( this->layers.size() == 0 ) this->inputLayer = this->outputLayer = layer; else this->outputLayer = layer; //push layer in vector this->layers.push_back ( layer ); for(int i = 0; i< layers.size();i++) if(layers[i] != NULL) cout << "Check::Layer[" << i << "] is not null!" << endl; } }; Second class: class Backpropagation : public Train { public: Backpropagation::Backpropagation ( FeedForwardNetwork* network ){ this->network = network; vector<FeedforwardLayer*> vec; network->getLayers(vec); } }; Now if i add from main() some layers into network via addLayer(..) method it's all good.My vector is just as it should.But after i call Backpropagation() constructor with a network object ,when i enter getLayers(), some of my objects from vector have their address set to NULL(they are randomly chosen:for example if i run my app once with 3 layer's into vector ,the first object from vector is null.If i run it second time first 2 objects are null,third time just first object null and so on). Now i can't explain why this is happening.I must say that all the objects that should be in vector they also live inside the network and they are not NULL; This happens everywhere after i done with addLayer() so not just in the getLayers(). I cant get a good grasp to this problem.I thought first that i might modify my vector.But i can't find such thing. Also why if the reference from vector is NULL ,the reference that lives inside ForwardNetwork as a linked list (inputLayer and outputLayer) is not NULL? I must ask for your help.Please ,if you have some advices don't hesitate! PS: as compiler i use g++ part of gcc 4.6.1 under ubuntu 11.10

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  • Updating a specific key/value inside of an array field with MongoDB

    - by Jesta
    As a preface, I've been working with MongoDB for about a week now, so this may turn out to be a pretty simple answer. I have data already stored in my collection, we will call this collection content, as it contains articles, news, etc. Each of these articles contains another array called author which has all of the author's information (Address, Phone, Title, etc). The Goal - I am trying to create a query that will update the author's address on every article that the specific author exists in, and only the specified author block (not others that exist within the array). Sort of a "Global Update" to a specific article that affects his/her information on every piece of content that exists. Here is an example of what the content with the author looks like. { "_id" : ObjectId("4c1a5a948ead0e4d09010000"), "authors" : [ { "user_id" : null, "slug" : "joe-somebody", "display_name" : "Joe Somebody", "display_title" : "Contributing Writer", "display_company_name" : null, "email" : null, "phone" : null, "fax" : null, "address" : null, "address2" : null, "city" : null, "state" : null, "zip" : null, "country" : null, "image" : null, "url" : null, "blurb" : null }, { "user_id" : null, "slug" : "jane-somebody", "display_name" : "Jane Somebody", "display_title" : "Editor", "display_company_name" : null, "email" : null, "phone" : null, "fax" : null, "address" : null, "address2" : null, "city" : null, "state" : null, "zip" : null, "country" : null, "image" : null, "url" : null, "blurb" : null }, ], "tags" : [ "tag1", "tag2", "tag3" ], "title" : "Title of the Article" } I can find every article that this author has created by running the following command: db.content.find({authors: {$elemMatch: {slug: 'joe-somebody'}}}); So theoretically I should be able to update the authors record for the slug joe-somebody but not jane-somebody (the 2nd author), I am just unsure exactly how you reach in and update every record for that author. I thought I was on the right track, and here's what I've tried. b.content.update( {authors: {$elemMatch: {slug: 'joe-somebody'} } }, {$set: {address: '1234 Avenue Rd.'} }, false, true ); I just believe there's something I am missing in the $set statement to specify the correct author and point inside of the correct array. Any ideas? **Update** I've also tried this now: b.content.update( {authors: {$elemMatch: {slug: 'joe-somebody'} } }, {$set: {'authors.$.address': '1234 Avenue Rd.'} }, false, true );

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  • Why is my program printing out the null termination character?

    - by Tyler Pfaff
    When I run this, it will SOMETIMES print out a null termination character. Most of the time it will, and probably 1/5 times it will print just the characters. void cryptogram::Encrypt(){ cout<<"encrypt"<tempS){ len=tempS.length(); int a=0; for(int j=0;j if(j!=len){ //if the word still has more characters j++; a=0; }else{ //if the word is done being scanned cout<<" "; } } } } } } } So that's it and this is the corresponding EXPECTED output that is printed SOMETIMES xvk bkikhxlr wggbtfkj wiylekgbdhx wjjm hko wigbtubxt xvk iwhj uedjkm glctb gvrmdiwhj iebbdielmeggtbx ctb xvtmk gbtubxvk wjjdxdthgbtubodll khvxvk imkbfdik xt xvk bkudth whj gbtfdjk hko tgxdthm whj tggtbxehdxdkm ctb mxejkhxmibdzdhtltur whj pemxdik mxejdkm mxdh cok wbk wlmt gbkgctb cteb hko zdh cgvrmdikjeiwhj qdhkmdtlturzzkjdydtivkzdmxbrw zdh zdjjlkkjeiwhj w jtixtbdh kjeiwjzdhdmxbittgkbodxv mjme whj eimj This is what normally prints though xvkÈ bkikhxlrÈ wggbtfkjÈ wiylekgbdhxÈ wjjmÈ hkoÈ wigbtubxtÈ xvkÈ iwhjÈ uedjkmÈ glctbÈ gvrmdiwhjÈ iebbdielmeggtbxÈ ctbÈ xvtmkÈ gbtubxvkÈ wjjdxdthgbtubodllÈ khvxvkÈ imkbfdikÈ xtÈ xvkÈ bkudthÈ whjÈ gbtfdjkÈ hkoÈ tgxdthmÈ whjÈ tggtbxehdxdkmÈ ctbÈ mxejkhxmibdzdhtlturÈ whjÈ pemxdikÈ mxejdkmÈ mxdhÈ cokÈ wbkÈ wlmtÈ gbkgctbÈ ctebÈ hkoÈ zdhÈ cgvrmdikjeiwhjÈ qdhkmdtlturzzkjdydtivkzdmxbrwÈ zdhÈ zdjjlkkjeiwhjÈ wÈ jtixtbdhÈ kjeiwjzdhdmxbittgkbodxvÈ mjmeÈ whjÈ eimj or some variation of an odd character at the end of each word This is what the cryptogram array is filled with by the way wyijkcuvdpqlzhtgabmxefonrs

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  • Is there a practical benefit to casting a NULL pointer to an object and calling one of its member fu

    - by zdawg
    Ok, so I know that technically this is undefined behavior, but nonetheless, I've seen this more than once in production code. And please correct me if I'm wrong, but I've also heard that some people use this "feature" as a somewhat legitimate substitute of a lacking aspect of the current C++ standard, namely, the inability to obtain the address (well, offset really) of a member function. For example, this is out of a popular implementation of a PCRE (Perl-compatible Regular Expression) library: #ifndef offsetof #define offsetof(p_type,field) ((size_t)&(((p_type *)0)->field)) #endif One can debate whether the exploitation of such a language subtlety in a case like this is valid or not, or even necessary, but I've also seen it used like this: struct Result { void stat() { if(this) // do something... else // do something else... } }; // ...somewhere else in the code... ((Result*)0)->stat(); This works just fine! It avoids a null pointer dereference by testing for the existence of this, and it does not try to access class members in the else block. So long as these guards are in place, it's legitimate code, right? So the question remains: Is there a practical use case, where one would benefit from using such a construct? I'm especially concerned about the second case, since the first case is more of a workaround for a language limitation. Or is it? PS. Sorry about the C-style casts, unfortunately people still prefer to type less if they can.

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  • Inserting records in Mysql with INSERT IGNORE and NULL values

    - by Homer1980ar
    I have a partitioned table InnoDB with several fields. I'm trying to avoid duplicates on insert. Let's say: Field1 int null Field2 int null Field3 int null Field4 int null Field5 int null I have created a UNIQUE index on those fields. I try to insert some records with NULL values and then try to reinsert them with IGNORE feature on MySql. Unfortunately it seems to replicated the records when using NULL values. If I try with zeros instead of NULL cases everything works, but I do need the nulls there. Any idea? Thanks, Leonardo

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  • JSF, writeAttribute("value", str, null) fails with strings obtained through ValueExpression.getValue

    - by Roma
    Hello, I'm having a somewhat weird problem with custom JSF component. Here's my renderer code: public class Test extends Renderer { public void encodeBegin(final FacesContext context, final UIComponent component) throws IOException { ResponseWriter writer = context.getResponseWriter(); writer.startElement("textarea", component); String clientId = component.getClientId(context); if (clientId != null) writer.writeAttribute("name", clientId, null); ValueExpression exp = component.getValueExpression("value"); if (exp != null && exp.getValue(context.getELContext()) != null) { String val = (String) exp.getValue(context.getELContext()); System.out.println("Value: " + val); writer.writeAttribute("value", val, null); } writer.endElement("textarea"); writer.flush(); } } The code generates: <textarea name="j_id2:j_id12:j_id19" value=""></textarea> Property binding contains "test" and as it should be, "Value: test" is successfully printed to console. Now, if I change the code to: public void encodeBegin(final FacesContext context, final UIComponent component) throws IOException { ResponseWriter writer = context.getResponseWriter(); writer.startElement("textarea", component); String clientId = component.getClientId(context); if (clientId != null) writer.writeAttribute("name", clientId, null); ValueExpression exp = component.getValueExpression("value"); if (exp != null && exp.getValue(context.getELContext()) != null) { String val = (String) exp.getValue(context.getELContext()); String str = "new string"; System.out.println("Value1: " + val + ", Value2: " + str); writer.writeAttribute("value", str, null); } writer.endElement("textarea"); writer.flush(); } generated html is: <textarea name="j_id2:j_id12:j_id19" value="new string"></textarea> and console output is "Value1: test, Value2: new string" What's going on here? This doesn't make sense. Why would writeAttribute differentiate between the two strings? Additional info: The component extends UIComponentBase I am using it with facelets

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  • Good case for a Null Object Pattern? (Provide some service with a mailservice)

    - by fireeyedboy
    For a website I'm working on, I made an Media Service object that I use in the front end, as well as in the backend (CMS). This Media Service object manipulates media in a local repository (DB); it provides the ability to upload/embed video's and upload images. In other words, website visitors are able to do this in the front end, but administrators of the site are also able to do this in the backend. I'ld like this service to mail the administrators when a visitor has uploaded/embedded a new medium in the frontend, but refrain from mailing them when they upload/embed a medium themself in the backend. So I started wondering whether this is a good case for passing a null object, that mimicks the mail funcionality, to the Media Service in the backend. I thought this might come in handy when they decide the backend needs to have implemented mail functionality as well. In simplified terms I'ld like to do something like this: Frontend: $mediaService = new MediaService( new MediaRepository(), new StandardMailService() ); Backend: $mediaService = new MediaService( new MediaRepository(), new NullMailService() ); How do you feel about this? Does this make sense? Or am I setting myself up for problems down the road?

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  • What are some commonly used source code check-in policies?

    - by rwmnau
    I'm curious what code review policies other development shops apply to their source code when it's checked into the source control repository. I'm setting up a TFS (Team Foundation) server, and I'd like to apply some check-in policies to start to stamp out bad practices. For example, I was thinking of starting with the following couple, so this is the kind of stuff I'm looking for: Prohibit empty "Catch" blocks. This would prevent applications from swallowing any exceptions without at least requiring a comment explaining why it's not necessary to do anything with the exception. Prohibit "Catch ex as Exception" generic exception handling. Instead, require code to catch specific types of exceptions and deal with them appropriately, instead of just building catch-all handling. Require a check-in comment. This one should be self-explanatory, though it seems that TFS (and most other source-control systems) don't require a comment by default. While these are just examples, they're where I'm thinking of starting, and while I'd like some additional examples of what's popular, I'm open to feedback on these. Also, though we're a mostly .NET shop, I imagine the popular policies are universal across languages and IDEs (we have some Java development and a few people who will use the repository develop with Eclipse).

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  • Greatest not null column

    - by Álvaro G. Vicario
    I need to update a row with a formula based on the largest value of two DATETIME columns. I would normally do this: GREATEST(date_one, date_two) However, both columns are allowed to be NULL. I need the greatest date even when the other is NULL (of course, I expect NULL when both are NULL) and GREATEST() returns NULL when one of the columns is NULL. This seems to work: GREATEST(COALESCE(date_one, date_two), COALESCE(date_two, date_one)) But I wonder... am I missing a more straightforward method?

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  • crontab still sending emails even with > /dev/null

    - by user2344668
    I have a crontab (root) that runs a script and output is set to /dev/null but I always get the emails whenever it runs. I only want to receive error emails. # Rackspace driveclient update (12pm MST) 0 12 * * * /root/scripts/driveclient-update > /dev/null The only way I can get it to turn off is to use /dev/null 2&1 but then I won't get error emails. This is happening on three different CentOS servers, two are 6.3 and one is 6.4. NOTE: I have read over and over that /dev/null is supposed to send stdout there and prevent the email if there is nothing but stdout from the script, so at works for at least some people; I cannot figure out why it is not working on these servers. Here's an example of where /dev/null is supposed to work: http://www.alphadevx.com/a/384-Suppressing-Cron-Job-Email-Notifications

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  • /dev/null file became regular file

    - by user197719
    In our production server suddenly /dev/null became a regular file and due to this sshd service got stopped and not able to login the server. And also we tried to the below steps to configure back to character device file, rm -rf /dev/null mknod /dev/null c 1 3 As soon as we run the rm command /dev/null is being re-created as a regular file before mknod can run. We can't figure out how this happening and which component is creating this file. So until we solve this issue we are unable to create /dev/null as character device file.

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  • Handling null values and missing object properties in Silverlight 4

    - by PeterTweed
    Before Silverlight 4 to bind a data object to the UI and display a message associated with either a null value or if the binding path was wrong, you would need to write a Converter.  In Silverlight 4 we find the addition of the markup extensions TargetNullValue and FallbackValue that allows us to display a value when a null value is found in the bound to property and display a value when the property being bound to is not found. This post will show you how to use both markup extensions. Steps: 1. Create a new Silverlight 4 application 2. In the body of the MainPage.xaml.cs file replace the MainPage class with the following code:     public partial class MainPage : UserControl     {         public MainPage()         {             InitializeComponent();             this.Loaded += new RoutedEventHandler(MainPage_Loaded);         }           void MainPage_Loaded(object sender, RoutedEventArgs e)         {             person p = new person() { NameValue = "Peter Tweed" };             this.DataContext = p;         }     }       public class person     {         public string NameValue { get; set; }         public string TitleValue { get; set; }     } This code defines a class called person with two properties.  A new instance of the class is created, only defining the value for one of the properties and bound to the DataContext of the page. 3.  In the MainPage.xaml file copy the following XAML into the LayoutRoot grid:         <Grid.RowDefinitions>             <RowDefinition Height="60*" />             <RowDefinition Height="28*" />             <RowDefinition Height="28*" />             <RowDefinition Height="30*" />             <RowDefinition Height="154*" />         </Grid.RowDefinitions>         <Grid.ColumnDefinitions>             <ColumnDefinition Width="86*" />             <ColumnDefinition Width="314*" />         </Grid.ColumnDefinitions>         <TextBlock Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="32,0,0,0" Name="textBlock1" Text="Name Value:" VerticalAlignment="Top" />         <TextBlock Grid.Row="2" Height="23" HorizontalAlignment="Left" Margin="32,0,0,0" Name="textBlock2" Text="Title Value:" VerticalAlignment="Top" />         <TextBlock Grid.Row="3" Height="23" HorizontalAlignment="Left" Margin="32,0,0,0" Name="textBlock3" Text="Non Existant Value:" VerticalAlignment="Top" />         <TextBlock Grid.Column="1" Grid.Row="1" Height="23" HorizontalAlignment="Left" Name="textBlock4" Text="{Binding NameValue, TargetNullValue='No Name!!!!!!!'}" VerticalAlignment="Top" Margin="6,0,0,0" />         <TextBlock Grid.Column="1" Grid.Row="2" Height="23" HorizontalAlignment="Left" Name="textBlock5" Text="{Binding TitleValue, TargetNullValue='No Title!!!!!!!'}" VerticalAlignment="Top" Margin="6,0,0,0" />         <TextBlock Grid.Column="1" Grid.Row="3" Height="23" HorizontalAlignment="Left" Margin="6,0,0,0" Name="textBlock6" Text="{Binding AgeValue, FallbackValue='No such property!'}" VerticalAlignment="Top" />    This XAML defines three textblocks – two of which use the TargetNull and one that uses the FallbackValue markup extensions.  4. Run the application and see the person name displayed as defined for the person object, the expected string displayed for the TargetNullValue when no value exists for the boudn property and the expected string displayed for the FallbackValue when the property bound to is not found on the bound object. It's that easy!

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  • How to create a bash script to check the SSH connection?

    - by chutsu
    I am in the process of creating a bash script that would log into the remote machines and create private and public keys. My problem is that the remote machines are not very reliable, and they are not always up. I need a bash script that would check if the SSH connection is up. Before actually creating the keys for future use.

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  • How to check SERP position correctly?

    - by Cengiz Frostclaw
    I wonder how do you check your website's SERP position for a certain query. I cannot directly go to Google and search, because it knows i'm looking for my site, and it shows it in the first position, but from another browser, it cannot be even in the first page. So how do you check for "average user" ? I use Tor browser for that, since it gives me a completely different IP, do you think is it safe? I mean, does it give useful information ?

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