ef-model-first

问题 This question already has answers here : Finding the reason for DBUpdateException (7 answers) Closed last month . I have problem, I have just started learning EF Model First and Im staying in one point for some time. I got such error : "An error occurred while updating the entries. See the inner exception for details" I have created an easy model on diagram, generated the database and wrote easy code in C# to add just one row in the table but the error is showing up all the time. I post

问题 I am trying my hardest to find the simplest way to create a basic "model first" entity framework example. However I am struggling with the actually generation of the database, particularly the running of the SQL against the database. Tools Visual Studio 2010 SQL Server 2008 Express Process Create a new class project Add a new Server-Database item (mdf) named "Database1.mdf" to the project Add an empty ADO.net Entity Model Create a simple entity (Person: Id, Name) Generate the Script selecting

问题 I am trying my hardest to find the simplest way to create a basic "model first" entity framework example. However I am struggling with the actually generation of the database, particularly the running of the SQL against the database. Tools Visual Studio 2010 SQL Server 2008 Express Process Create a new class project Add a new Server-Database item (mdf) named "Database1.mdf" to the project Add an empty ADO.net Entity Model Create a simple entity (Person: Id, Name) Generate the Script selecting

问题 Desired outcome: Use model first approach with Entity Framework and allow changes to deployed database/ model to be done automatically based on the changes in the model. Automatic schema difference script generation to allow smooth migrations. Is there a way to perform migrations in model first EF6? I can see code first migrations topics all over, but nothing much on Model First. Options I saw so far: Database generation power pack (seems outdated) somehow convert to code first, then use

问题 I have been using Entity Framework model first since VS 2010. When I build my project, EF generates a Model.Designer.cs file containing all entities. This designer file also contains the documentation added to the entities in the EDMX file. When I created a new EF model first project in VS 2012, a Model.tt file is added to my EDMX file. This T4 template generates a single file for every entity in my model. Unfortunately, the documentation from the EDMX file is not used in the generated code.

问题 I have an existing model and initially generated the database from this model and had populated the existing tables with some data. Now I've added a new table to the model. Is there a way to update the database from the new model without losing all the data in the existing tables? Thanks. 回答1: EF's default database generation workflow creates a full script that will recreate your database every time you select Generate Database from Model... so if you execute it in your DB you will lose all

问题 EF has generated for me some partial classes, each with a constructor, but it says not to touch them (example below), now if I make my own secondary partial class and I want to have a constructor that automatically sets some of the fields how do I do so as it would conflict? //------------------------------------------------------------------------------ // <auto-generated> // This code was generated from a template. // // Manual changes to this file may cause unexpected behavior in your

问题 I am trying to create data model for a graph with Node and Edge. If Edge does not contain any property I can simply create many-to-many association from a Node to itself. However I want to store some properties on the Edge e.g. Distance. I tried to create another entity but didn't find a way to declare the relationship between Edge and Node. Is it possible in Model First? How? 回答1: You must create two one-to-many associations from Node to Edge to model self referencing many-to-many relation

问题 MVC3 project, using LINQ to Entity, and Entity Framework 4 Code-First. In another post ( Return products which belong to all tags in a list using LINQ ), I received assistance in creating a LINQ statement to return a subset of data. The LINQ is syntactically correct and compiles, but generates incorrect SQL. Specifically, it makes reference to a non-existent table. If I correct the table name, it returns the correct data, so the LINQ seems to be correct. Note in the interest of keeping this

问题 This is a long question, but I would be very very thankful if I can get some good advice on this. In short, I’m looking for a good approach for version upgrade of MS SQL database schema that also demands data being moved from deleted tables into new tables. I think Stack Overflow is the most appropriate place for this question (not dba.stackexchange.com) because at its core, this is an issue for .NET developers using Entity Framework, and the database parts of this consists mostly of auto