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  • Huge page buffer vs. multiple simultaneous processes

    - by Andrei K.
    One of our customer has a 35 Gb database with average active connections count about 70-80. Some tables in database have more than 10M records per table. Now they have bought new server: 4 * 6 Core = 24 Cores CPU, 48 Gb RAM, 2 RAID controllers 256 Mb cache, with 8 SAS 15K HDD on each. 64bit OS. I'm wondering, what would be a fastest configuration: 1) FB 2.5 SuperServer with huge buffer 8192 * 3500000 pages = 29 Gb or 2) FB 2.5 Classic with small buffer of 1000 pages. Maybe some one has tested such case before and will save me days of work :) Thanks in advance.

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  • Using now() in a <asp:textbox>

    - by Anthony
    Can anyone help. I am using a formview in VS 2005. I have different elements in my form databound to a database and I am performing an INSERT SQL statement. No problem. The problem is that I am trying to enter the current date into the SQL statement and I am having a problem. I can add <%now()% to the "Text" property of the asp:Textbox. But when I do, then I can't bind the textbox to a specific database column. How do I do both???? I can do this: <asp:TextBox ID="TextBox2" runat="server" Text='<%# Bind("Initiate_Date") %>' ></asp:TextBox> Or this: <asp:TextBox ID="TextBox2" runat="server" Text='<%# now() %>' ></asp:TextBox> But I don't know how to do both.

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  • Losing DateTimeOffset precision when using C#

    - by Darvis Lombardo
    I have a SQL Server table with a CreatedDate field of type DateTimeOffset(2). A sample value which is in the table is 2010-03-01 15:18:58.57 -05:00 As an example, from within C# I retrieve this value like so: var cmd = new SqlCommand("SELECT CreatedDate FROM Entities WHERE EntityID = 2", cn); var da = new SqlDataAdapter(cmd); DataTable dt =new DataTable(); da.Fill(dt); And I look at the value: MessageBox.Show(dt.Rows[0][0].ToString()); The result is 2010-03-01 15:18:58 -05:00, which is missing the .57 that is stored in the database. If I look at dt.Rows[0][0] in the Watch window, I also do not see the .57, so it appears it has been truncated. Can someone shed some light on this? I need to use the date to match up with other records in the database and the .57 is needed. Thanks! Darvis

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  • Linq ChangeConflictException occurs when submitting DataContext changes

    - by Alex
    System.Data.Linq.ChangeConflictException: 2 of X updates failed. at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode) at PROJECT.Controllers.HomeController.ClickProc(Int32 id, String code, String n) This is what I get very often. This action is done thousands of times a day, and I get this exception about once every 5 seconds. From what I understand it happens when something changes in the database in the period between creating DataContext and updating it. Am I right? How can I fix it? Update I just debugged the error and found the following: Table name: dbo.Stats current value: 9852039 original value: 9852038 database value: 9852039 The Stats table is updated constantly. So how can I still make LINQ save the changes. With "classical" SQL Server access through SqlDataCommand I never had problems like that.

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  • Should I stick only to AWS RDS Automated Backup or DB Snapshots?

    - by James Wise
    I am using AWS RDS for MySQL. With it comes on backup, I understand that amazon provides two types of backup - automated backup and database (DB) snapshot. The difference is explain in here - http://aws.amazon.com/rds/faqs/#23. However, I am still confuse if should I stick to automated backup only or both automated and manual (db snapshots). What do you think guys? What's the setup of your own? I heard to others that automated backup is not reliable due to some unrecoverable database when the DB instance is crashed so the DB snapshots are the way to rescue you. If I will do daily DB snapshots as similar settings to automated backup, I have gonna pay much bunch of bucks. Hope anyone could enlighten me or advise me the right set up. Thanks. James

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  • Using Durable Services for saving wcf instances

    - by miker169
    I am currently creating a service which connects to a DAL and that can run a few stored procedures, one of the issues I am facing is that for certain times of the month, we can't update the database, (at the moment this is done manually. This is done via the user adding a note to their calendar) But I would like to automate this process, one of the possible solutions I can think of using is a durable service. When the date is lets say the 1st of the month, the Update/Insert/Delete instances can get saved to a database, and then ran after that date in a batch. Is this the intended use of durable services ? Is there a better route I could possibly take ?

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  • Trouble dragging and dropping gui components onto other .net forms using NHibernate

    - by IsaacB
    Hi, using VS2008, here. I have a GUI component that loads some stuff from a database mapped by nhibernate in its constructor. When I drag and drop this component onto another form from the toolbox, NHibernate complains that it can't find the config file in program files\visual studio 9\common7\ide. Why is it looking here for the cfg file? I'm actually calling database stuff through another project in the same solution, and the cfg file is located at the root of that project. copy/pasting the cfg file over to there does work, but I'm working with svn here and I don't want to have configuration files outside the repository. Something else that would help would be turning off how it tries to load the data in the form design screen. How would I do that?

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  • Django paging object has issues with Postgresql QuerySets

    - by pivotal
    I have some django code that runs fine on a SQLite database or on a MySQL database, but it runs into problems with Postgres, and it's making me crazy that no one has has this issue before. I think it may also be related to the way querysets are evaluated by the pager. In a view I have: def index(request, page=1): latest_posts = Post.objects.all().order_by('-pub_date') paginator = Paginator(latest_posts, 5) try: posts = paginator.page(page) except (EmptyPage, InvalidPage): posts = paginator.page(paginator.num_pages) return render_to_response('blog/index.html', {'posts' : posts}) And inside the template: {% for post in posts.object_list %} {# some rendering jazz #} {% endfor %} This works fine with SQLite, but Postgres gives me: Caught TypeError while rendering: 'NoneType' object is not callable To further complicate things, when I switch the Queryset call to: latest_posts = Post.objects.all() Everything works great. I've tried re-reading the documentation, but found nothing, although I admit I'm a bit clouded by frustration at this point. What am I missing? Thanks in advance.

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  • InnoDB not supported by webhost. What now?

    - by Peter Perhác
    I was developing a small WAMP web application on my laptop, where I have an instance of mySQL running and I chose InnoDB for my DB engine. After several weeks' development I wanted to make it available to the public and found out the database server provided by my web host does not support InnoDB, only MyISAM. The create-and-populate script generated from the innoDB schema on my laptop, when executed against the live database, can manage to create individual TABLES but then runs into problems creating the VIEWs. Are views not supported in MyISAM? I know FOREIGN KEYs are not. That's very much why I made the choice of InnoDB... What are my chances of making my innoDB schema design work with myISAM? Is there any straightforward way of converting the whole schema from one storage engine to the other? Should I look for another web host that does provide a mysql db that supports innoDB?

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  • How can I access the value of a checkbox without a postback?

    - by Starwfanatic
    I have a radgrid controlling access to an application for users. There are two columns, a 'name' column and a checkbox 'access' column representing their current access permission. the checkboxes are populated from a database. I would like the to change the checkboxes to grant or deny access to the users I specify. Since there are alot of users I would like to make multiple changes and use a submit button to write the changes to the database. I do not want to postback with each checkbox change and wait for the page to "blink". My problem is that with the checkbox postback disabled, when I click submit, the value of the checkboxes are not registering the changes I make. I need a way to access the current client-side state of the checkbox or some workaround to accomplish this. Thanks in advance!

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  • MySQL driver for Rails in Windows 7 x64

    - by Darth
    I've got problem with connecting to MySQL database on my freshly installed Windows 7 machine. I'm getting this error when I try to migrate my database. !!! The bundled mysql.rb driver has been removed from Rails 2.2. Please install the mysql gem and try again: gem install mysql. rake aborted! 193: %1 is not valid Win32 application - C:/Ruby/lib/ruby/gems/1.8/gems/mysql-2.8.1-x86-mswin32/lib/1.8/mysql_api.so I currently have installed ruby 1.8.6 (2008-08-11 patchlevel 287) [i386-mswin32] mysql version 5.0.86 for Win64 gem 1.3.1 mysql-2.8.1-x86-mswin32

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  • SQL error C# - Parameter already defined

    - by jakesankey
    Hey there. I have a c# application that parses txt files and imports the data from them into a sql db. I was using sqlite and am now working on porting it to sql server. It was working fine with sqlite but now with sql i am getting an error when it is processing the files. It added the first row of data to the db and then says "parameter @PartNumber has already been declared. Variable names must be unique within a batch or stored procedure". Here is my whole code and SQL table layout ... the error comes at the last insertCommand.ExecuteNonQuery() instance at the end of the code... SQL TABLE: CREATE TABLE Import ( RowId int PRIMARY KEY IDENTITY, PartNumber text, CMMNumber text, Date text, FeatType text, FeatName text, Value text, Actual text, Nominal text, Dev text, TolMin text, TolPlus text, OutOfTol text, FileName text ); CODE: using System; using System.Data; using System.Data.SQLite; using System.IO; using System.Text.RegularExpressions; using System.Threading; using System.Collections.Generic; using System.Linq; using System.Data.SqlClient; namespace JohnDeereCMMDataParser { internal class Program { public static List<string> GetImportedFileList() { List<string> ImportedFiles = new List<string>(); using (SqlConnection connect = new SqlConnection(@"Server=FRXSQLDEV;Database=RX_CMMData;Integrated Security=YES")) { connect.Open(); using (SqlCommand fmd = connect.CreateCommand()) { fmd.CommandText = @"IF (EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'RX_CMMData' AND TABLE_NAME = 'Import')) BEGIN SELECT DISTINCT FileName FROM Import; END"; fmd.CommandType = CommandType.Text; SqlDataReader r = fmd.ExecuteReader(); while (r.Read()) { ImportedFiles.Add(Convert.ToString(r["FileName"])); } } } return ImportedFiles; } private static void Main(string[] args) { Console.Title = "John Deere CMM Data Parser"; Console.WriteLine("Preparing CMM Data Parser... done"); Console.WriteLine("Scanning for new CMM data... done"); Console.ForegroundColor = ConsoleColor.Gray; using (SqlConnection con = new SqlConnection(@"Server=FRXSQLDEV;Database=RX_CMMData;Integrated Security=YES")) { con.Open(); using (SqlCommand insertCommand = con.CreateCommand()) { SqlCommand cmdd = con.CreateCommand(); string[] files = Directory.GetFiles(@"C:\Documents and Settings\js91162\Desktop\", "R303717*.txt*", SearchOption.AllDirectories); List<string> ImportedFiles = GetImportedFileList(); foreach (string file in files.Except(ImportedFiles)) { string FileNameExt1 = Path.GetFileName(file); cmdd.CommandText = @" IF (EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'RX_CMMData' AND TABLE_NAME = 'Import')) BEGIN SELECT COUNT(*) FROM Import WHERE FileName = @FileExt; END"; cmdd.Parameters.Add(new SqlParameter("@FileExt", FileNameExt1)); int count = Convert.ToInt32(cmdd.ExecuteScalar()); con.Close(); con.Open(); if (count == 0) { Console.WriteLine("Parsing CMM data for SQL database... Please wait."); insertCommand.CommandText = @" INSERT INTO Import (FeatType, FeatName, Value, Actual, Nominal, Dev, TolMin, TolPlus, OutOfTol, PartNumber, CMMNumber, Date, FileName) VALUES (@FeatType, @FeatName, @Value, @Actual, @Nominal, @Dev, @TolMin, @TolPlus, @OutOfTol, @PartNumber, @CMMNumber, @Date, @FileName);"; insertCommand.Parameters.Add(new SqlParameter("@FeatType", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@FeatName", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@Value", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@Actual", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@Nominal", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@Dev", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@TolMin", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@TolPlus", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@OutOfTol", DbType.Decimal)); string FileNameExt = Path.GetFullPath(file); string RNumber = Path.GetFileNameWithoutExtension(file); string RNumberE = RNumber.Split('_')[0]; string RNumberD = RNumber.Split('_')[1]; string RNumberDate = RNumber.Split('_')[2]; DateTime dateTime = DateTime.ParseExact(RNumberDate, "yyyyMMdd", Thread.CurrentThread.CurrentCulture); string cmmDate = dateTime.ToString("dd-MMM-yyyy"); string[] lines = File.ReadAllLines(file); bool parse = false; foreach (string tmpLine in lines) { string line = tmpLine.Trim(); if (!parse && line.StartsWith("Feat. Type,")) { parse = true; continue; } if (!parse || string.IsNullOrEmpty(line)) { continue; } Console.WriteLine(tmpLine); foreach (SqlParameter parameter in insertCommand.Parameters) { parameter.Value = null; } string[] values = line.Split(new[] { ',' }); for (int i = 0; i < values.Length - 1; i++) { SqlParameter param = insertCommand.Parameters[i]; if (param.DbType == DbType.Decimal) { decimal value; param.Value = decimal.TryParse(values[i], out value) ? value : 0; } else { param.Value = values[i]; } } insertCommand.Parameters.Add(new SqlParameter("@PartNumber", RNumberE)); insertCommand.Parameters.Add(new SqlParameter("@CMMNumber", RNumberD)); insertCommand.Parameters.Add(new SqlParameter("@Date", cmmDate)); insertCommand.Parameters.Add(new SqlParameter("@FileName", FileNameExt)); // insertCommand.ExecuteNonQuery(); } } } Console.WriteLine("CMM data successfully imported to SQL database..."); } con.Close(); } } } }

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  • Gujarati Font Rendering

    - by Vishal Khakhkhar
    I am having sqlite database containing gujarati words.. The sql query for the database is... BEGIN TRANSACTION; CREATE TABLE eng_guj (_id INTEGER PRIMARY KEY, eng_word , guj_word ); INSERT INTO eng_guj VALUES(1,'aardvark','??? ??????? ?????????? ?? ?????? ????? ??????.'); COMMIT; I want to display the text in textview.. but its not rendering properly.. meant Its displaying the word in gujarati like "???????" will be displayed as "??????". I already have used Typeface and different ttf fonts.

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  • How can I handle multiple views of a data object? Which design pattern is acceptable?

    - by tranquil.byte
    I have a person object. class Person { private $name; ... } I need to be able to change how they are displayed on the front-end ( visitors have control ). They can choose list view, grid view, photo view for example. class PersonDisplay { public function displayList() { // Query database // Output html to display in list mode } public function displayPhoto() { // Query database // Output html to display in photo mode } } Is this an acceptable way to handle the presentation of the items on the front-end or is there a specific design pattern I should be researching to help me with this task? Does anyone have any suggestions or ideas where this could go wrong or if this could potentially make maintenance a nightmare? The Person object was just an example very similiar to what I am using.

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  • MySQL - Calculating fields on the fly vs storing calculated data

    - by Christian Varga
    Hi Everyone, I apologise if this has been asked before, but I can't seem to find an answer to a question that I have about calculating on the fly vs storing fields in a database. I read a few articles that suggested it was preferable to calculate when you can, but I would just like to know if that still applies to the following 2 examples. Example 1. Say you are storing data relating to a car. You store the fuel tank size in litres, and how many litres it uses per 100km. You also want to know how many KMs it can travel, which can be calculated from the tank size and economy. I see 2 ways of doing this: When a car is added or updated, calculate the amount of KMs and store this as a static field in the database. Every time a car is accessed, calculate the amount of KMs on the fly. Because the cars economy/tank size doesn't change (although it could be edited), the KMs is a pretty static value. I don't see why we would calculate it every single time the car is accessed. Wouldn't this waste cpu time as opposed to simply storing it in a separate field in the database and calculating only when a car is added or updated? My next example, which is almost an entirely different question (but on the same topic), relates to counting children. Let's say we have a app which has categories and items. We have a view where we display all the categories, and a count of all the items inside each category. Again, I'm wondering what's better. To perform a MySQL query to count all the items in each category every single time the page is accessed? Or store the count in a field in the categories table and update when an item is added / deleted? I know it is redundant to store anything that can be calculated, but I worry that calculating fields or counting records might be slow as opposed to storing the data in a field. If it's not then please let me know, I just want to learn about when to use either method. On a small scale I guess it wouldn't matter either way, but apps like Facebook, would they really count the amount of friends you have every time someone views your profile or would they just store it as a field? I'd appreciate any responses to both of these scenarios, and any resource that might explain the benefits of calculating vs storing. Thanks in advance, Christian

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  • Changing Data in ListView

    - by legr3c
    Hi In my app I use a ListView to display data from the database. The data changes sometimes, for example when the user applies new filters or changes the sorting method. I use AsyncTask to get the databsase cursor that points to the new data set because sometimes data needs to be loaded from the net which can take some time. What I do now looks something like this: private class updateTask extends AsyncTask<Void, Void, Void> { /* * runs on the UI thread before doInBackground */ @Override protected void onPreExecute(){ // prepare some stuff... } /* * runs in a separate thread * used for time-consuming loading operation */ @Override protected Void doInBackground() { //get new database cursor mCursor = mDbAdapter.getCursor(); return null; } /* * runs on the UI thread after doInBackground */ @Override protected void onPostExecute(Void result){ if(mCursor!=null){ MyActivity.this.startManagingCursor(mCursor); mCursorAdapter = new MyCustomCursorAdapter(MyActivity.this, mCursor); mListView.setAdapter(mCursorAdapter); } } } This works so far but I realize that creating a new CursorAdapter and calling setAdapter on my ListView each time isn't the correct way to do it. Also, after setAdapter the scroll position of the list is set back to the top. I found this post which describes how to do it properly. So now I want to do something like this: onCreate(){ // ... // create the CursorAdapter using null as the initial cursor MyCustomCursorAdapter cursorAdapter = new MyCustomCursorAdapter(this, null); mListView.setAdapter(cursorAdapter); // ... } private class updateTask extends AsyncTask<Void, Void, Void> { /* * runs on the UI thread before doInBackground */ @Override protected void onPreExecute(){ // prepare some stuff... } /* * runs in a separate thread * used for time-consuming loading operation */ @Override protected Void doInBackground() { //get new database cursor mCursor = mDbAdapter.getCursor(); return null; } /* * runs on the UI thread after doInBackground */ @Override protected void onPostExecute(Void result){ // this returns null! MyCustomCursorAdapter cursorAdapter = (MyCustomCursorAdapter)mListView.getAdapter(); Cursor oldCursor = cursorAdapter.getCursor(); if(oldCursor!=null){ MyActivity.this.stopManagingCursor(oldCursor); oldCursor.close(); } if(mCursor!=null){ MyActivity.this.startManagingCursor(mCursor); cursorAdapter.changeCursor(mCursor); } } } This however doesn't work for me because (MyCustomCursorAdapter)mListView.getAdapter(); always returns null. Why does this happen? What am I doing wrong? Edit: Some additional information: my adapter implements SectionIndexer. I don't really think that this has anything to do with my problem but it has caused me some troubles before so I thought I'd mention it.

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  • Java/MySQL: Working with data in classes

    - by skiwi
    What is the best way to deal with accessing/modifying tables in a database? I have read about the Data Access Object approach, but none of the resources I have found so far indicate a clear implementation of it. So assume you have a database with a table called accounts that has columns id, name, password and email. How would you properly access it within Java? I mean most people know how to do SQL statements, but that is not really the point. I hope people here can be of help. Regards.

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  • How to persist non-trivial fields in Play Framework

    - by AlexR
    I am trying to persist complex objects using Ebeans in Play Framework (2.03). In particular, I've created a class that contains a field of type weka.classifier.Classifier (Weka is a popular machine learning library - see http://weka.sourceforge.net/doc/weka/classifiers/Classifier.html). Classifier implements Serializeable so I hoped that I can get away with something like @Entity @Table(name = "classifiers") public class ClassifierData extends Model { @Id public Long id; public Classifier classifier; } However, the Evolutions script suggests the following database structure: create table classifiers ( id bigint auto_increment not null, constraint pk_classifiers primary key (id)) ) In other words, it ignores the field of type Classifier. (The database is MySQL if it makes any difference) What should I do to store complex serializeable objects using Ebean/Evolutions/PlayFramework?

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  • From comma separated list to individual item result set. *mysql

    - by Raziel
    I'm doing some data migration from a horribly designed database to a less horribly designed database. There is a many to many relationship that has a primary key in one table that corresponds to a comma separated list in another. FK_ID | data ------------- 1,2 | foo 3 | bar 1,3,2 | blarg Is there a way to output the FK_ID field with each comma separated element as a single line in the result set? result set FK_ID | data ------------- 1 | foo 2 | foo 3 | bar 1 | blarg 2 | blarg 3 | blarg I'm thinking this would require some sort of recursive query which I don't think mysql has. Thanks in advance.

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  • Cannot copying tables when compiling on Device

    - by Amarpreet
    Hi guys, I am working on sqlite application with around 10 tables in database. it works fine when i run on simulator. And when i open the sqlite file from Applications folder of simulator it shows me all the tables and data. the problem arises when i run app on device. I downloaded the application from device and i checked the sqlite database files there were no tables in it. please help me solving this problem. thanks.

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  • Flex DataGrid reads a field from lastResult.node as number

    - by Nemi
    Why Flex 3 DataGrid reads a string from XML lastResult.node as number? A field is saved as var_char in mysql, php reads it as string and pass it OK. If there are more then 16 charaters it gets rounded.... For example: this in database cell: 12345678901234567 gets read in DataGrid as nubmer as 12345678901234568 this is in database cell: 5555544444222223333377777 php reads it same and puts it in XML flex reads XML into arrayCollection and DataGrid reads it as: 5.55554444422222e+24 So it reads it as number, why? And how to make it read as String? I tried with labelFunction, no help.

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  • How to compare a string column(as DateTime) in LINQ?

    - by lyon
    I have a database with a ValidDate field - it's a string(we made a mistake, it should be a datetime, but we can't modify the database now.) and now I want to compare this filed with a parameter(validDateStart) from the website: priceList = priceList.Where(p => Convert.ToDateTime(p.ValidDate) >= Convert.ToDateTime(validDateStart)); var list = initPriceList.ToList(); But I get an error: The method ToDateTime is not implemented. Can anybody give me some help? Thanks!

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  • Is a many-to-many relationship with extra fields the right tool for my job?

    - by whichhand
    Previously had a go at asking a more specific version of this question, but had trouble articulating what my question was. On reflection that made me doubt if my chosen solution was correct for the problem, so this time I will explain the problem and ask if a) I am on the right track and b) if there is a way around my current brick wall. I am currently building a web interface to enable an existing database to be interrogated by (a small number of) users. Sticking with the analogy from the docs, I have models that look something like this: class Musician(models.Model): first_name = models.CharField(max_length=50) last_name = models.CharField(max_length=50) dob = models.DateField() class Album(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) class Instrument(models.Model): artist = models.ForeignKey(Musician) name = models.CharField(max_length=100) Where I have one central table (Musician) and several tables of associated data that are related by either ForeignKey or OneToOneFields. Users interact with the database by creating filtering criteria to select a subset of Musicians based on data the data on the main or related tables. Likewise, the users can then select what piece of data is used to rank results that are presented to them. The results are then viewed initially as a 2 dimensional table with a single row per Musician with selected data fields (or aggregates) in each column. To give you some idea of scale, the database has ~5,000 Musicians with around 20 fields of related data. Up to here is fine and I have a working implementation. However, it is important that I have the ability for a given user to upload there own annotation data sets (more than one) and then filter and order on these in the same way they can with the existing data. The way I had tried to do this was to add the models: class UserDataSets(models.Model): user = models.ForeignKey(User) name = models.CharField(max_length=100) description = models.CharField(max_length=64) results = models.ManyToManyField(Musician, through='UserData') class UserData(models.Model): artist = models.ForeignKey(Musician) dataset = models.ForeignKey(UserDataSets) score = models.IntegerField() class Meta: unique_together = (("artist", "dataset"),) I have a simple upload mechanism enabling users to upload a data set file that consists of 1 to 1 relationship between a Musician and their "score". Within a given user dataset each artist will be unique, but different datasets are independent from each other and will often contain entries for the same musician. This worked fine for displaying the data, starting from a given artist I can do something like this: artist = Musician.objects.get(pk=1) dataset = UserDataSets.objects.get(pk=5) print artist.userdata_set.get(dataset=dataset.pk) However, this approach fell over when I came to implement the filtering and ordering of query set of musicians based on the data contained in a single user data set. For example, I could easily order the query set based on all of the data in the UserData table like this: artists = Musician.objects.all().order_by(userdata__score) But that does not help me order by the results of a given single user dataset. Likewise I need to be able to filter the query set based on the "scores" from different user data sets (eg find all musicians with a score 5 in dataset1 and < 2 in dataset2). Is there a way of doing this, or am I going about the whole thing wrong?

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