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• Many to Many Association Tables - Is it customary to put additional columns in these tables?

  - by Randy Minder

  We've encountered the following situation in our database. We have table 'A' and table 'B' which have a M2M relationship. The association table is named 'AB' and contains a FK column to table 'A' and a FK column to table 'B'. Now we've identified a need to store additional data about this association. For example, a date when the association occurred, and who made the association etc. We've decided to put these additional columns in the 'AB' association table. However, something tells me this is frowned upon by database purists. On the other hand, it makes no sense to us to create yet an additional table to store this associated data. What's the prevailing thought on this?

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• "ref" vs "out" keyword errors using the sql-net and C# Sqlite combination for windows phone 7.1

  - by param

  I am getting some "ref" vs "out" keyword errors using the sql-net and C# Sqlite combination for windows phone 7.1. Is this due to a wrong combination of libraries that I am using? App Type: Windows Phone 7.1 Using: 1) sql-net Version 1.0.5, Source Nuget thru Visual Studio 2) C# Sqlite for WP7 (wp7sqlite) ( Community.CSharpSqlite.WP7) Version 0.1.1, Source Nuget thru Visual Studio. The exact error I receive is below **Error 5 The best overloaded method match for Community.CsharpSqlite.Sqlite3.sqlite3_open(string, ref Community.CsharpSqlite.Sqlite3.sqlite3)' has some invalid arguments C:\Dev\Learning\SQLite.cs Line:2492 Column: 29 ** The next error then hints that it is related to the parameter being passed as "out" type instead of "ref" type. Error 6 Argument 2 must be passed with the 'ref' keyword C:\Dev\Learning\SQLite.cs Line: 2492 Column: 64 I can make the compile errors go away by replacing the "out" keyword with the "ref" keyword, but that is likely to lead to other issues. Given that I do not see much complain about this issue - I may be doing something wrong but not able to detect easily. Thanks, Parmeshwar

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• Custom Expression in Linq-to-Sql Designer

  - by csharpnoob

  According to Microsoft: http://msdn.microsoft.com/de-de/library/system.data.linq.mapping.columnattribute.expression.aspx It's possible to add expression to the Linq-to-SQL Mapping. But how to configure or add them in Visual Studio in the Designer? Problem, when I add it manual to thex XYZ.designer.cs it on change it will be lost. //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:2.0.50727.4927 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ This is generated: [Column(Name="id", Storage="_id", DbType="Int")] public System.Nullable<int> id { ... But i need something like this [Column(Name="id", Storage="_id", DbType="Int", Expression="Max(id)")] public System.Nullable<int> id { ... Thanks.

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• How would I detect horizontal-black lines using ImageMagick?

  - by Zando

  So I have what is essentially a spreadsheet in TIFF format. There is some uniformity to it...for example, all the column widths are the same. I want to de-limit this sheet by those known-column widths and basically create lots of little graphic files, one for each cell, and run OCR on them and store it into a database. The problem is that the horizontal lines are not all the same height, so I need to use some kind of graphics library command to check if every pixel across is the same color (i.e. black). And if so, then I know I've reached the height-delimiter for a cell. How would I go about doing that? (I'm using RMagick)

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• In Elixir or SQLAlchemy, is there a way to also store a comment for a/each field in my entities?

  - by kchau

  Our project is basically a web interface to several systems of record. We have many tables mapped, and the names of each column aren't as well named and intuitive as we'd like... The users would like to know what data fields are available (i.e. what's been mapped from the database). But, it's pointless to just give them column names like: USER_REF1, USER_REF2, etc. So, I was wondering, is there a way to provide a comment in the declaration of my field? E.g. class SegregationCode(Entity): using_options(tablename="SEGREGATION_CODES") segCode = Field(String(20), colname="CODE", ... primary_key=True) #Have a comment attr too? If not, any suggestions?

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• Turning A Stacked List into workable data

  - by BoSox

  In Excel I have a list of names that in the cell appear stacked, and I want each name in its own column. I was thinking Python may be a good way to do this? Example: Joe Smith John Hawk Mike Green Lauren Smith One cell will look exactly like that, with each name on its line within the cell but all of the names contained in the cell. I have 50 cells each with 1-20 stacked names and I want to put each name in its own cell on a given row. So, in my example all of those names would occupy the same row but each would have their own column. Any ideas?

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• Is it possible to partition more than one way at a time in SQL Server?

  - by meeting_overload

  I'm considering various ways to partition my data in SQL Server. One approach I'm looking at is to partition a particular huge table into 8 partitions, then within each of these partitions to partition on a different partition column. Is this even possible in SQL Server, or am I limited to definining one parition column+function+scheme per table? I'm interested in the more general answer, but this strategy is one I'm considering for Distributed Partitioned View, where I'd partition the data under the first scheme using DPV to distribute the huge amount of data over 8 machines, and then on each machine partition that portion of the full table on another parition key in order to be able to drop (for example) sub-paritions as required.

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• Update source with TemplateBinding

  - by Polaris

  I use this style for all my labels <Style TargetType="Label" x:Key="LabelStyle"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="Label"> <StackPanel Orientation="Horizontal" > <TextBox Loaded="MyTextBlock_Loaded" x:Name="EditControl" Visibility="Collapsed" Text="{TemplateBinding Tag}" /> <Label Content="{TemplateBinding Content}" Grid.Column="1" Grid.Row="1"> </Label> </StackPanel> </ControlTemplate> </Setter.Value> </Setter> </Style> and my sample label <Label Grid.Column="0" Grid.Row="0" Content="Photo" Style="{StaticResource LabelStyle}" Tag="{Binding fieldsCode.firstName, UpdateSourceTrigger=PropertyChanged}"/> But I feel that TemplateBiding doesn't support update of property. How can solve this issue

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• NHibernate cascade and inverse

  - by Kordonme

  I have three mappings as follows: public MainChapterMap() { // other properties HasMany(x => x.ClientSpecific).KeyColumn("MainChapterId"); } public MainChapterClientMap() { // other properties References(x => x.MainChapter).Column("MainChapterId"); HasMany(x => x.Details).KeyColumn("MainChapterClientId"); } public MainChapterClientDetailMap() { // other properties References(x => x.MainChapterClient).Column("MainChapterClientId"); } MainChapter has many client-specific chapters. The client-specific chapters (MainChapterClient) has many translations (MainChapterClientDetail) The dele rules should be as follow: When deleting a MainChapter Delete the MainChapterClient row Delete the MainChapterClientDetail row(s) When deleting a MainChapterClient Do NOT delete the MainChapter row Delete the MainChapterClientDetail row(s) When deleting a MainChapterClientDetail Do NOT delete the MainChapter row Do NOT delete the MainChapterClientDetail row(s) But I no matter what I end up getting this error: deleted object would be re-saved by cascade (remove deleted object from associations)[Entities.MainChapterClient#39] I'm not sure how to set up my cascades anymore. Any help are more than welcomed!

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• How do you write multiple lists from Matlab to the same excel file?

  - by Ben Fossen

  I have several lists in Matlab that I want to write to the same excel file. I have one list xordered and another list aspl. I do not know the length of the lists till after I run the Matlab program. I used data = xlswrite('edgar.xls',fliplr(sortedx'),'A2:A3000') for the first list but when I tried to write another list to the same file like this I ended up with two different excel files named edgar.xls asp_data = xlswrite('edagr.xls', fliplr(aspl'), 'B2:B3000') Is there a way I can write both of these lists into the same excel file? xordered in the A column and aspl in the B column?

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• MySQL: Count two things in one query?

  - by Nebs

  I have a "boolean" column in one of my tables (value is either 0 or 1). I need to get two counts: The number of rows that have the boolean set to 0 and the number of rows that have it set to 1. Currently I have two queries: One to count the 1's and the other to count the 0's. Is MySQL traversing the entire table when counting rows with a WHERE condition? I'm wondering if there's a single query that would allow two counters based on different conditions? Or is there a way to get the total count along side the WHERE conditioned count? This would be enough as I'd only have to subtract one count from the other (due to the boolean nature of the column). There are no NULL values. Thanks.

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• Plural to Singular conversion trouble in Rails Migrations?

  - by Earlz

  Hi, I'm a beginner at Ruby On Rails and am trying to get a migration to work with the name Priorities So, here is the code I use in my migration: class Priorities < ActiveRecord::Migration def self.up create_table :priorities do |t| t.column :name, :string, :null => false, :limit => 32 end Priority.create :name => "Critical" Priority.create :name => "Major" Priority.create :name => "Minor" end def self.down drop_table :priorities end end This results in the following error though: NOTICE: CREATE TABLE will create implicit sequence "priorities_id_seq" for serial column "priorities.id" NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "priorities_pkey" for table "priorities" rake aborted! An error has occurred, this and all later migrations canceled: uninitialized constant Priorities::Priority Is this some problem with turning ies to y for converting something plural to singular?

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• rails: date type and GetDate

  - by cbrulak

  This is a follow up to this question: http://stackoverflow.com/questions/2930256/unique-responses-rails-gem I'm going to create an index based on the user id, url and a date type. I want date type (not datetime type) because I want the day, the 24 hour day to be part of the index to avoid duplication of page views counts on the same day. In other words: A view only counts once in a day by a visitor. I also want the default value of that column (viewdate) to be the function GETDATE(). This is what I have in my migration: execute "ALTER TABLEpage_viewsADD COLUMN viewdate datetime DEFAULTGETDATE()`" But the value viewdate is always empty. What am I missing? (as an aside, any other suggestions for accomplishing this goal?)

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• Numpy modify array in place?

  - by User

  I have the following code which is attempting to normalize the values of an m x n array (It will be used as input to a neural network, where m is the number of training examples and n is the number of features). However, when I inspect the array in the interpreter after the script runs, I see that the values are not normalized; that is, they still have the original values. I guess this is because the assignment to the array variable inside the function is only seen within the function. How can I do this normalization in place? Or do I have to return a new array from the normalize function? import numpy def normalize(array, imin = -1, imax = 1): """I = Imin + (Imax-Imin)*(D-Dmin)/(Dmax-Dmin)""" dmin = array.min() dmax = array.max() array = imin + (imax - imin)*(array - dmin)/(dmax - dmin) print array[0] def main(): array = numpy.loadtxt('test.csv', delimiter=',', skiprows=1) for column in array.T: normalize(column) return array if __name__ == "__main__": a = main()

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• How to create custom exception handler for custom controls or extension methods.

  - by Shantanu Gupta

  I am creating an extension method in C# to retrieve some value from datagridview. Here if a user gives column name that doesnot exists then i want this function to throw an exception that can be handled at the place where this function will be called. How can i achieve this. public static T Value<T>(this DataGridView dgv, int RowNo, string ColName) { if (!dgv.Columns.Contains(ColName)) throw new ArgumentException("Column Name " + ColName + " doesnot exists in DataGridView."); return (T)Convert.ChangeType(dgv.Rows[RowNo].Cells[ColName].Value, typeof(T)); }

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• Entity Framework doesn't like 0..1 to * relationships.

  - by Orion Adrian

  I have a database framework where I have two tables. The first table has a single column that is an identity and primary key. The second table contains two columns. One is a nvarchar primary key and the other is a nullable foreign key to the first table. On the default import of the database I get the following error: Condition cannot be specified for Column member 'ForeignKeyId' because it is marked with a 'Computed' or 'Identity' StoreGeneratedPattern. where ForeignKeyId is the second foreign key reference in the second table. Is this just something the entity model doesn't do? Or am I missing something?

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• nHibernate one-to-many inserts but doesnt update

  - by user210713

  Instead of getting into code, I have a simple question. Default behavior for a simple one-to-many is that it inserts the child record then updates the foreign key column with the parent key. Has anyone ever had a one-to-many where the child object gets inserted but not updated resulting in a row in my table with a null in the foreign key column? I want the default behaviour for a standard one-to-many. I don't want to have to add the parent as a property to the child. Thanks.

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• Fastest way to display a full calendar

  - by Aurélien Ribon

  Hello, I need to display a complete calendar (12 months, 31~ days/month) on screen. Currently, I'm using a 12-column grid, with each column filled with a "months" stackpanel. Each "month" stackpanel is filled with 31 (or less) day representations. Each day representation is composed of a DockPanel embedding three controls : a textblock to display the day letter a textblock to display the day number a textblock to display a short message Of course, performances are crushed down when I try to resize the window. Is there a useful trick to allow a fast display of many textblocks ?

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• R counting the occurrences of similar rows of data frame

  - by Matt

  I have data in the following format called DF (this is just a made up simplified sample): eval.num, eval.count, fitness, fitness.mean, green.h.0, green.v.0, offset.0 random 1 1 1500 1500 100 120 40 232342 2 2 1000 1250 100 120 40 11843 3 3 1250 1250 100 120 40 981340234 4 4 1000 1187.5 100 120 40 4363453 5 1 2000 2000 200 100 40 345902 6 1 3000 3000 150 90 10 943 7 1 2000 2000 90 90 100 9304358 8 2 1800 1900 90 90 100 284333 However, the eval.count column is incorrect and I need to fix it. It should report the number of rows with the same values for (green.h.0, green.v.0, and offset.0) by only looking at the previous rows. The example above uses the expected values, but assume they are incorrect. How can I add a new column (say "count") which will count all previous rows which have the same values of the specified variables? I have gotten help on a similar problem of just selecting all rows with the same values for specified columns, so I supposed I could just write a loop around that, but it seems inefficient to me.

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• How can you query for an object using one of its properties' id

  - by James Smith

  I have two entities, say, House and People, where multiple people can live in one house. It's a unidirectional link where each Person has a field for which House they belong to, so the Person table has a column named house_id. I need to be able to return all the Person objects who belong to a certain House, but I only have the id of the house. This can be done like this: House house = houseDAO.findById(houseId); List people = session.createCriteria(Person.class).add(Restrictions.eq("house", house)).list(); But since I don't need the house, that's adding an unnecessary query. I've tried to do: session.createCriteria(Person.class).add(Restrictions.eq("house_id", houseId)).list(); But that doesn't work because house_id is not a property, it's a database column. I could just add an sql restriction, but is there a hibernate way of doing this?

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• ASP .net MVC Jqgrid data binding

  - by SARAVAN

  Hi, I am using a jqgrid with a column named 'Comments'. My controller code returns data as follows: var jsonData = new { rows= .... .... select new { col1.... col2.... Comments = _Model.GetComments(id), }) ....... ..... return Json(jsonData, JsonRequestBehavior.AllowGet); } _Model.GetComments(id) will return a ClientComments Object which has a few properties say CommentID, FirstName, MiddleName etc., which will be bound to each row in the grid Now in my jqgrid I need to build a tool tip based on Comments column properties and for that I need to use the properties of my Comments in JQGrid for each row. May I know How I can manipulate Comment's properties for each row? Any help would be appreciated. I tried in my javascript that for each row rowObject.Comments.FirstName and it did not work.

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• Sending BLOBs in a JSON service,... how?

  - by Marten Sytema

  Hello I have a webservice (ie. servlet) implemented in Java. It gets some data from a MySQL table, with one column being of type BLOB (an image), and some other columns are just plain text. Normally I would store the file outside the database with a pointer to it in the database, but due to circumstance I now have to use this BLOB column... What is the proper way to send this? How to encode the image in a JSONObject, and how to parse (and RENDER!) it on the otherside ? I want to use JSONP, to avoid having to proxy it through the consumer's webserver. So that the consumer can just put in a tag pointing to the webservice, calling a callback. Any thoughts how to handle images in this situation? Also thoughts on performance etc. are interesting!

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• Will MyISAM type tables work better than InnoDB for large numbers of columns?

  - by Ethan

  I have a MySQL InnoDB table with 238 columns. 56 of them are TEXT type, 27 are VARCHAR(255). I am getting MySQL error 139 when users insert data sometimes. After research I found that I'm probably running into InnoDB row size/column size/column count limitations. (I'm putting it that way because the specific limits among those three things are interdependent.) Docs on InnoDB give an idea of the limits. If I switch this table to MyISAM is it likely to solve the problem? I understand the maximum row size of 65,535 bytes. I think I'm hitting InnoDB's additional 8000 byte limit somehow. Switching to PostgreSQL is also a remote option, but would take much longer.

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• SQL SELECT across two tables

  - by Brett Spurrier

  Hi there, I am a little confused as to how to approach this SQL query. I have two takes (equal number of records), and I would like to return a column with which is the division between the two. In other words, here is my not-working-correctly query: SELECT( (SELECT v FROM Table1) / (SELECT DotProduct FROM Table2) ); How would I do this? All I want it a column where each row equals the same row in Table1 divided by the same row in Table2. The resulting table should have the same number of rows, but I am getting something with a lot more rows than the original two tables. I am at a complete loss. Any advice?

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• Is it possible to mix orm.xml definitions with annotations when using JPA/hibernate ?

  - by hatchetman82

  I'm working on an application whihc supports using several DB vendors, with the table definitions being different for each DB type. The trouble is that the column definitions are not what hibernate expects, and so my entities contain a lot of @Column(..columnDefintion="..."...) annotations. To further complicate the issue, there's no way to specify a columnDefinition per DB. So I tried moving just the columnDefinition bits to an orm.xml file, and I have a Maven profile that bundles the correct file. JBoss 4.0.5/Hibernate 3.2.0GA fails to validate, and it seems it completely disregards the annotations given an xml file. Is there a way to make Hibernate "merge" the data from the xml with the annotations ?

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