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  • populate object graph from database

    - by Rama
    Hi, I would like to know the best way to populate an object that has a collection of child objects and each child object may inturn have a collection of objects, from database without making multiple calls to the database to get child objects for each object. basically in hierarchical format something like for example a customer has orders and each order has order items. is it best to retrieve the data in xml format (SQL server 2005), or retrieve a dataset by joining the related tables together and then map that the data to the object? thanks in advance for your help.

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  • logfile deleted on Oracle database how to re-create it?

    - by Daniel
    for my database assignment we were looking into 'database corruption' and I was asked to delete the second redo log file which I have done with the command: rm log02a.rdo this was in the $HOME/ORADATA/u03 directory. Now I started up my database using startup pfile=$PFILE nomount then I mounted it using the command alter database mount; now when I try to open it alter database open; it gives me the error: ORA-03113: end-of-file on communication channel Process ID: 22125 Session ID: 25 Serial number: 1 I am assuming this is because the second redo log file is missing. There is still log01a.rdo, but not the one I have deleted. How can I go about recovering this now so that I can open my database again? I have looked into the database created scripts, and it specified the log02a.rdo file to be size 10M and part of group 2. If I do select group#, member from v$logfile; I get: 1 /oradata/student_db/user06/ORADATA/u03/log01a.rdo 2 /oradata/student_db/user06/ORADATA/u03/log02a.rdo 3 /oradata/student_db/user06/ORADATA/u03/log03a.rdo 4 /oradata/student_db/user06/ORADATA/u03/log04a.rdo So it is part of group 2. If I try to add the log02a.rdo file again "already part of the database". If I drop group 2 and then add it again with these commands: ALTER DATABASE ADD LOGFILE GROUP 2 ('$HOME/ORADATA/u03/log02a.rdo') SIZE 10M; Nothing. Supposedly alters the database, but it still won't start up. Any ideas what I can do to re-create this and be able to open my database again?

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  • SQL Server architecture guidance

    - by Liam
    Hi, We are designing a new version of our existing product on a new schema. Its an internal web application with possibly 100 concurrent users (max)This will run on a SQL Server 2008 database. On of the discussion items recently is whether we should have a single database of split the database for performance reasons across 2 separate databases. The database could grow anywhere from 50-100GB over 5 years. We are Developers and not DBAs so it would be nice to get some general guidance. [I know the answer is not simple as it depends on the schema, archiving policy, amount of data etc. ] Option 1 Single Main Database [This is my preferred option]. The plan would be to have all the tables in a single database and possibly to use file groups and partitioning to separate the data if required across multiple disks. [Use schema if appropriate]. This should deal with the performance concerns One of the comments wrt this was that the a single server instance would still be processing this data so there would still be a processing bottle neck. For reporting we could have a separate reporting DB but this is still being discussed. Option 2 Split the database into 2 separate databases DB1 - Customers, Accounts, Customer resources etc DB2 - This would contain the bulk of the data [i.e. Vehicle tracking data, financial transaction tables etc]. These tables would typically contain a lot of data. [It could reside on a separate server if required] This plan would involve keeping the main data in a smaller database [DB1] and retaining the [mainly] read only transaction type data in a separate DB [DB2]. The UI would mainly read from DB1 and thus be more responsive. [I'm aware that this option makes it harder for Referential Integrity to be enforced.] Points for consideration As we are at the design stage we can at least make proper use of indexes to deal performance issues so thats why option 1 to me is attractive and its more of a standard approach. For both options we are considering implementing an archiving database. Apologies for the long Question. In summary the question is 1 DB or 2? Thanks in advance, Liam

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  • Connecting form to database errors

    - by Russell Ehrnsberger
    Hello I am trying to connect a page to a MySQL database for newsletter signup. I have the database with 3 fields, id, name, email. The database is named newsletter and the table is named newsletter. Everything seems to be fine but I am getting this error Notice: Undefined index: Name in C:\wamp\www\insert.php on line 12 Notice: Undefined index: Name in C:\wamp\www\insert.php on line 13 Here is my form code. <form action="insert.php" method="post"> <input type="text" value="Name" name="Name" id="Name" class="txtfield" onblur="javascript:if(this.value==''){this.value=this.defaultValue;}" onfocus="javascript:if(this.value==this.defaultValue){this.value='';}" /> <input type="text" value="Enter Email Address" name="Email" id="Email" class="txtfield" onblur="javascript:if(this.value==''){this.value=this.defaultValue;}" onfocus="javascript:if(this.value==this.defaultValue){this.value='';}" /> <input type="submit" value="" class="button" /> </form> Here is my insert.php file. <?php $host="localhost"; // Host name $username="root"; // Mysql username $password=""; // Mysql password $db_name="newsletter"; // Database name $tbl_name="newsletter"; // Table name // Connect to server and select database. mysql_connect("$host", "$username", "$password")or die("cannot connect"); mysql_select_db("$db_name")or die("cannot select DB"); // Get values from form $name=$_POST['Name']; $email=$_POST['Email']; // Insert data into mysql $sql="INSERT INTO $tbl_name(name, email)VALUES('$name', '$email')"; $result=mysql_query($sql); // if successfully insert data into database, displays message "Successful". if($result){ echo "Successful"; echo "<BR>"; echo "<a href='index.html'>Back to main page</a>"; } else { echo "ERROR"; } ?> <?php // close connection mysql_close(); ?>

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  • Comparing date in access database

    - by Simon
    How can i compare the day in the access database to a given day in c#? The date column in the database is an general date(day/month/year) try { database = new OleDbConnection(connectionString); database.Open(); date = DateTime.Now.ToShortDateString(); string queryString = "SELECT user_name,zivila.naziv " + "FROM (users LEFT JOIN obroki_save ON obroki_save.ID_uporabnika=users.ID)" + " LEFT JOIN zivila ON zivila.ID=obroki_save.ID_zivila " + " WHERE users.ID= " + a.ToString() + " AND obroki_save.datum=# " + date; loadDataGrid(queryString); } catch (Exception ex) { MessageBox.Show(ex.Message); return; }

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  • Accessing property of object vs variable in javascript

    - by Samuel
    Why when I try to access a variable that don't exist, javascript throw an exception but when I try to access a property that don't exist in an object, javascript returns an undefined object? For example, this case returns an undefined object: function Foo(){ console.log(this.bar); } Foo(); But, in this other example, javascript throw an exception: function Foo(){ console.log(bar); } Foo(); ReferenceError: bar is not defined

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  • Database.ExecuteNonQuery does not return

    - by dan-waterbly
    I have a very odd issue. When I execute a specific database stored procedure from C# using SqlCommand.ExecuteNonQuery, my stored procedure is never executed. Furthermore, SQL Profiler does not register the command at all. I do not receive a command timeout, and no exeception is thrown. The weirdest thing is that this code has worked fine over 1,200,000 times, but for this one particular file I am inserting into the database, it just hangs forever. When I kill the application, I receive this error in the event log of the database server: "A fatal error occurued while reading the input stream from the network. The session will be terminated (input error: 64, output error: 0). Which makes me think that the database server is receiving the command, though SQL Profiler says otherwise. I know that the appropiate permissions are set, and that the connection string is right as this piece of code and stored procedure works fine with other files. Below is the code that calls the stored procedure, it may be important to note that the file I am trying to insert is 33.5MB, but I have added more than 10,000 files larger than 500MB, so I do not think the size is the issue: using (SqlConnection sqlconn = new SqlConnection(ConfigurationManager.ConnectionStrings["TheDatabase"].ConnectionString)) using (SqlCommand command = sqlconn.CreateCommand()) { command.CommandText = "Add_File"; command.CommandType = CommandType.StoredProcedure; command.CommandTimeout = 30 //should timeout in 30 seconds, but doesn't... command.Parameters.AddWithValue("@ID", ID).SqlDbType = SqlDbType.BigInt; command.Parameters.AddWithValue("@BinaryData", byteArr).SqlDbType = SqlDbType.VarBinary; command.Parameters.AddWithValue("@FileName", fileName).SqlDbType = SqlDbType.VarChar; sqlconn.Open(); command.ExecuteNonQuery(); } There is no firewall between the server making the call and the database server, and the windows firewalls have been disabled to troubleshoot this issue.

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  • c# - Object reference not set to an instance of an object.

    - by tom
    Line 30: sUsername.Trim(); Line 31: sPassword.Trim(); Line 32: string ConnectionString = WebConfigurationManager.ConnectionStrings["dbnameConnectionString"].ConnectionString; Line 33: SqlConnection myConnection = new SqlConnection(ConnectionString); Line 34: try Object reference not set to an instance of an object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. Any ideas? I don't understand the error.

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  • Using enums or a set of classes when I know I have a finite set of different options?

    - by devoured elysium
    Let's say I have defined the following class: public abstract class Event { public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } What would you prefer between this: public class AsleepEvent : Event { public AsleepEvent(DateTime time) : base(time) { } } public class AwakeEvent : Event { public AwakeEvent(DateTime time) : base(time) { } } and this: public enum StateEventType { NowAwake, NowAsleep } public class StateEvent : Event { protected StateEventType stateType; public MealEvent(DateTime time, StateEventType stateType) : base(time) { stateType = stateType; } } and why? I am generally more inclined to the first option, but I can't explain why. Is it totally the same or are any advantages in using one instead of the other? Maybe with the first method its easier to add more "states", altough in this case I am 100% sure I will only want two states: now awake, and now asleep (they signal the moments when one awakes and one falls asleep).

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  • How to access parent window variables from object

    - by Pickle
    I've got an XHTML 1.1 Strict document that is loading another XHTML 1.1 document in an <object> element (as <iframe> isn't part of the XHTML 1.1 spec). I'm having trouble in IE8 (don't care about 6 or 7) with accessing a javascript variable, Lightbox, in the parent window, from the document loaded in the <object>. In Firefox and everywhere I've seen online, I can just use window.parent.Lightbox. In IE8 however, I get it being undefined. window.parent does give me an object but it doesn't have my Lightbox variable. I've also tried window.Lightbox, window.top.Lightbox, and window.top.document.Lightbox, but all return undefined. I should mention I'm using Javascript to set the data property of the <object> - but I don't see how that could affect anything relevant. What Javascript Fu do I need to do to be able to access my Lightbox variable?

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  • Hibernate Updating an existing entity with a new object

    - by DD
    Hi, Assume I have an entity Foo in the DB. I am parsing some files and creating new Foo objects and would like to check if the parsed Foo object exists in the DB (using a unique attribute). If it exists already update it otherwise save as a new object. What is the best approach? Could I simply set the id and version in the new Foo object? Or would I be better off loading the Foo object from the DB and copying over the properties from the parsed file? Thanks.

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  • Synchronous database reads inside IHttpAsyncHandler

    - by sayao
    On asp.net if i call a synchronous database query inside an IHttpAsyncHandler with delegate.BeginInvoke, would it still release the asp.net worker thread while reading the database? For example, this post: http://madskristensen.net/post/How-to-use-the-IHttpAsyncHandler-in-ASPNET.aspx If i put a synchronous database call inside ServeContent, would the request still happen asynchronously?

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  • C#: why have all static methods/variables in a non-static class?

    - by Craig Johnston
    I have come across a class which is non-static, but all the methods and variables are static. Eg: public class Class1 { private static string String1 = "one"; private static string String2 = "two"; public static void PrintStrings(string str1, string str2) { ... All the variables are static across all instances, so there is no point having separate instances of the class. Is there any reason to create a class such as this?

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  • vs2003 : assign datarow object

    - by dotnet-practitioner
    currently I am doing this... object s = new object(); ... s = mydatarow["mycolumn"]; What I would like to do is... DataRow r = null; ... r = mydatarow["mycolumn"]; and I get an error saying that can not covert from object to DataRow.. is there a better way of doing this?

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  • How can I define an empty array in a Perl construtor?

    - by Laimoncijus
    I am just beginner with Perl, so if it sounds stupid - sorry for that :) My problem is - I am trying to write a class, which has an empty array, defined in constructor of a class. So I am doing this like this: package MyClass; use strict; sub new { my ($C) = @_; my $self = { items => () }; bless $self, ref $C || $C; } sub get { return $_[0]->{items}; } 1; Later I am testing my class with simple script: use strict; use Data::Dumper; use MyClass; my $o = MyClass->new(); my @items = $o->get(); print "length = ", scalar(@items), "\n", Dumper(@items); And while running the script I get following: $ perl my_test.pl length = 1 $VAR1 = undef; Why am I doing wrong what causes that I get my items array filled with undef? Maybe someone could show me example how the class would need to be defined so I would not get any default values in my array?

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  • jQuery find events handlers registered with an object

    - by ages04
    I need to find which event handlers an object has registered. eg. $("#el").click(function(){...}); $("#el").mouseover(function(){...}); Is there anyway I can use a function to find out that- $("#el") has click and mouseover registered and possibly iterate over the event handlers. If not a jQuery Object can we find this on a plain DOM object?

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  • Events in Classes (VB.NET)

    - by Otaku
    I find that I write a lot of code within my classes to keep properties in sync with each other. I've read about Events in Classes, but have not been able to wrap my head around how to make them work for what I'm looking for. I could use some advice here. For example, in this one I always want to keep myColor up to date with any change whatsoever in any or all of the Red, Green or Blue properties. Class myColors Private Property Red As Byte Private Property Green As Byte Private Property Blue As Byte Private Property myColor As Color Sub New() myColor = Color.FromArgb(0, 0, 0) End Sub Sub ChangeRed(ByVal r As Byte) Red = r myColor = Color.FromArgb(Red, Green, Blue) End Sub Sub ChangeBlue(ByVal b As Byte) Blue = b myColor = Color.FromArgb(Red, Green, Blue) End Sub End Class If one or more of those changes, I want myColor to be updated. Easy enough as above, but is there a way to work with events that would automatically do this so I don't have to put myColor = Color.FromArgb(Red, Green, Blue) in every sub routine?

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  • Partial class or "chained inheritance"

    - by Charlie boy
    Hi From my understanding partial classes are a bit frowned upon by professional developers, but I've come over a bit of an issue; I have made an implementation of the RichTextBox control that uses user32.dll calls for faster editing of large texts. That results in quite a bit of code. Then I added spellchecking capabilities to the control, this was made in another class inheriting RichTextBox control as well. That also makes up a bit of code. These two functionalities are quite separate but I would like them to be merged so that I can drop one control on my form that has both fast editing capabilities and spellchecking built in. I feel that simply adding the code form one class to the other would result in a too large code file, especially since there are two very distinct areas of functionality, so I seem to need another approach. Now to my question; To merge these two classes should I make the spellchecking RichTextBox inherit from the fast edit one, that in turn inherits RichTextBox? Or should I make the two classes partials of a single class and thus making them more “equal” so to speak? This is more of a question of OO principles and exercise on my part than me trying to reinvent the wheel, I know there are plenty of good text editing controls out there. But this is just a hobby for me and I just want to know how this kind of solution would be managed by a professional. Thanks!

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