EF problem with entity re-ordering and uniqueness constraint

Posted by wpfwannabe on Stack Overflow See other posts from Stack Overflow or by wpfwannabe
Published on 2010-03-20T15:25:52Z Indexed on 2010/03/20 15:31 UTC
Read the original article Hit count: 317

Filed under:

entity-framework

|

sql

I am using Entity Framework and I've come to an interesting stumbling block. Let's say there is a db table "Item" with "sequence" column of type int (and others of course). Column "sequence" must be unique and it is used for (re)ordering of items.

EF maps this table to "Item" class with "sequence" int property. Now let's say I want to swap position of two items by mutually exchanging each other's sequence number. Upon calling SaveChanges() EF throws an exception complaining about "sequence" uniqueness. It probably generates two UPDATEs and the first one probably fails.

I assume that plain SQL solution to this issue is using a third UPDATE to introduce a unique sequence value in the process but I am stuck with EF.

Any thoughts?

© Stack Overflow or respective owner

Related posts about entity-framework

Differences Between NHibernate and Entity Framework

as seen on ASP.net Weblogs - Search for 'ASP.net Weblogs'
Introduction NHibernate and Entity Framework are two of the most popular O/RM frameworks on the .NET world. Although they share some functionality, there are some aspects on which they are quite different. This post will describe this differences and will hopefully help you get started with the one… >>> More
Entity Framework & Binding syncronisation

as seen on Stack Overflow - Search for 'Stack Overflow'
* EDIT * Sorry, I should make it clearer. Imagine I have an entity: public class MyObject { public string Name { get; set; } } And I have a ListBox: <ListBox x:Name="lbParts"> <ListBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Name}"/> … >>> More
Joins and UI Binding with the Entity Framework

as seen on Internet.com - Search for 'Internet.com'
Learn how to build queries with the Entity Framework that involve multiple tables as well as binding in the UI with the EntityDataSource. >>> More
Frederick .NET User Group April 2010 Meeting

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
FredNUG is pleased to announce that we have an excellent speaker lined up for April. On April 20th, we’ll start with pizza and social networking at 6:30 PM. Then, starting at 7 PM, Dane Morgridge will present “Getting Started with Entity Framework 4” The scheduled agenda is: 6:30 PM - 7:00… >>> More
[News] NHibernate vs MS Entity Framework

as seen on Dot Net Guru - Search for 'Dot Net Guru'
Voil? une question qui se posera de plus en plus avec la sortie prochaine de .NET V4 et Entity Framework V4, l'outil de mapping objet/relationnel de Microsoft. M?me s'il est vrai que l'opinion de Ayende peut para?tre biais?e du fait qu'il est contributeur NHibernate, son point de vue et surtout ses… >>> More

Related posts about sql

SQL SERVER – Concat Strings in SQL Server using T-SQL – SQL in Sixty Seconds #035 – Video

as seen on SQL Authority - Search for 'SQL Authority'
Concatenating string is one of the most common tasks in SQL Server and every developer has to come across it. We have to concat the string when we have to see the display full name of the person by first name and last name. In this video we will see various methods to concatenate the strings. SQL… >>> More
SQL SERVER – Concat Function in SQL Server – SQL Concatenation

as seen on SQL Authority - Search for 'SQL Authority'
Earlier this week, I was delivering Advanced BI training on the subject of “SQL Server 2008 R2″. I had great time delivering the session. During the session, we talked about SQL Server 2010 Denali. Suddenly one of the attendees suggested his displeasure for the product. He said, even though… >>> More
Error with SQL Server Setup 2012 on Windows 2012

as seen on Server Fault - Search for 'Server Fault'
I am trying to install SQL Server on Windows 2012. I was able to finally get the wizard up and running after making some changes on the server, but now it fails no matter what I do with the following error: TITLE: SQL Server Setup failure. SQL Server Setup has encountered the following error: … >>> More
How can I detect which version of SQL (eg SQL 2008 or SQL Azure)

as seen on Stack Overflow - Search for 'Stack Overflow'
I need to detect which version of SQL I am dealing with to perorm various tasks, I need specifically detect if I am on SQL 2008 or SQL Azure. How can I do this with detection code written in SQL? >>> More
Nested SQL Select statement fails on SQL Server 2000, ok on SQL Server 2005

as seen on Stack Overflow - Search for 'Stack Overflow'
Here is the query: INSERT INTO @TempTable SELECT UserID, Name, Address1 = (SELECT TOP 1 [Address] FROM (SELECT TOP 1 [Address] FROM [UserAddress] ua INNER JOIN UserAddressOrder uo ON ua.UserID = uo.UserID WHERE ua.UserID = u.UserID ORDER BY uo.AddressOrder ASC) q ORDER BY AddressOrder… >>> More