What is the best way to manually generate Primary Keys in Entity Framework 4.1 Code First?
I am programming ASP.NET MVC 3 and I use a repository pattern.
I currently generate keys in a sequential order by using the [code]....
I'm trying to update one value of a compound primary key from within the entity framework and I'm getting this error: "The property 'CustomerID' is part of the object's key information and cannot be modified. "[code]...
View 4 RepliesEntity Splitting: one class, two or more tables.Here is how it is done in C#, but I need to get it working in vb.net.One more thing: the class name and table columns do not match, so I have to be able to map that out, too.I have to get this to work this way because the place I'm working at right now is a vb.net only shop and the database schema is fubar, but they have so much (millions) of lines of code done directly against the database in both asp classic, vb.net, AND asp.net webforms that changing the schema right now is not realistically possible.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Post>()
.Map(m =>
[code]....
I have a simple Entity Framework. For simplicity's sake I will transform the entity names to Northwind Like.I have a IEnumerable Of Customer and Item Objects
View 1 RepliesOn a client i have an anonymous list containing a multi-column primary key previously selected from the DB.Then i need to select all the records from the DB that equals the primary key list i have stored in the memory.[code]
View 1 Repliesc# - Are Microsoft Entity Framework and ADO.NET Entity Framework (.edmx) the same?
View 7 RepliesIn entity framework we can use 3 approaches model first , code first , database first but each one of them needs manual hand touch(means creating database or create model or write the POCO class codes or entity class codes) before proceeding to the next step ( using EF in context ).What if I want to create database and tables and table relationships programatically and still want to have to features of EntityFramework 4.3.
To be more specific ,from this example http://support.microsoft.com/kb/307283 we can create database , tables and everything using SQL command but we can't have the advantages of entity framework. So if we want to have that what should we do? To give the ability to create dynamic table fields those steps will not be sufficient. In all 3 steps database , table and table columns are fixed. There is no way that a user can create new tables or columns dynamically. http:[url].... in this post , it shows how to create manual db, tables and etc using SQL but it is based on ADO.NET but I want Entity Manager to do that.
I am using Entity Framework 4.1 code first+MVC3 and the inheritence stratagy that I use is TPC
I have the following classes
Public Class ObjectBase
<Key()>
Public Property Id As Integer
Public Property Description As String
End Class
[Code]...
Question 1 (and question 2) should be very simple, but I have allready spent hours on Google to find an answer with no result at all. The only thing I have found is that you can get all computers in ObjectBase by writing context.ObjectBase.OfType(Of Computer), and that does not help since you cannot write context.BorrowObjects.ObjectBase.OfType(Of Computer) code samples in VB.NET (if you can), but more importantly: Please ensure that the codesamples you supply work without hours of modification!
I have in my database a table (AccessControl) that describes a sort of users "access control list" for the informations contained in the table Customers and other tables.Example: the entity CUSTOMER is marked by the EntityId #1. If a user belongs to the department #6, he can access the records of customer #16 and #31, but he can't for #14, that can viewed by user in department #3:
[code]...
How can I describe this relationship into the DbContext definition using a fluent Code First approach?
I want to update an entity without loading the entity from the database first. I've accomplished this but only by knowing all of the entities properties and then using the "attachto" method. My issues is i don't want my app to need to remember all of the properties. Example:
[Code]....
I am trying to jump from ASP Classic to asp.net. I have followed tutorials to get Entity Framework and LINQ to connect to my test database, but I am having difficulties figuring out ExecuteQuery(). I believe the problem is that I need an "entity class" for my database, but I can't figure out how to do it. Here is my simple code:
Dim db as New TestModel.TestEntity
Dim results AS IEnumerable(OF ???) = db.ExecuteQuery(Of ???)("Select * from Table1")
From the microsoft example site, they use an entity class called Customers, but I don't understand what that means.
SELECT
T.TABLE_NAME as TableName,
T.CONSTRAINT_NAME as CONSTRAINT_NAME,
K.COLUMN_NAME as FieldName,
K.ORDINAL_POSITION
FROM
INFORMATION_SCHEMA.TABLE_CONSTRAINTS T
INNER JOIN
INFORMATION_SCHEMA.KEY_COLUMN_USAGE K
ON T.CONSTRAINT_NAME = K.CONSTRAINT_NAME
WHERE
T.CONSTRAINT_TYPE = 'PRIMARY KEY'
AND T.TABLE_NAME = 'mytable'
ORDER BY
T.TABLE_NAME,
K.ORDINAL_POSITION
Query for getting pk of a table. When I Run this query to fill dataset from dataadapter it does not return any value while it returns a row when executed from sql server. Fill method is called correctly as it is working from past 8 months and no problem is yet is there any special property of dataadapter. I also used to put above query in a sp and when try to execute that sp the result was sq not found.
Is it possible to manually download the Microsoft Framework 3.5 or 4.0 ? That would be useful in order to have it during installation of a program . I know that when installing a VB .NET program , it asks to connect and download it , if the PC does not have it already . The problem is that some people have a very slow connection speed or don't even have any connection . Therefore it would be useful to have that installation kit in order to supply it along with program itself .
View 5 RepliesI need to include my application in a custom Preinstallation Environment I am creating. The problem is that in order to include the framework within my PE would require a ton of extra work plus increase the size by a huge amount.I know that you can use an application like XenoCode to include the framework dependencies, but the cost of their software is pretty high.
View 7 RepliesEDIT: was a design issueI am undergoing a computing project for Alevel computing.The project consists of a 6 tabled Microsoft access database. I am using vb.net to code the application for a student tracking system.My ERD is below:My problem: How to insert a new compound Primary key into a existing table?If I increment StudID and CourseID in tblContact then I need to increment them in tblStudentCourse which leads to records not pointing to the right directions..For enforcing the relationships I am using the .relations with the dataset.
'Student - StudentCourse
DS.Relations.Add(New DataRelation("StudStudCorRelation", DTStudents.Columns("StudID"), DTStudentCourses.Columns("StudID"), True))
[code].....
anyone know how sql pick a random number of primary keys, I know get max number and call a random number work but what if there a missing numbers like 1,2,4,6,7 so max 5 and random will missing 6 and 7 also there a error if 3 and 5 come up.
View 1 Repliesi have a project where I need to concatenate strings from 4 different tables based on a sequence of numbers. I created a 5th table that holds the number sequence and dictates in what order the strings get appended. I have created primary keys on the tables, but 3 of the tables are composite primary keys. I have written up to where I start referencing the primary keys, but am not sure how I should reference the keys on the actual tables. I saw some examples for creating composite keys from an array which I did. The main questions are did I declare the composite keys correctly, am I creating the composite key reference from the array correctly, and how should I reference it all to append to the stringbuilder variable.
[Code]...
And yes I kn ow it would be easier if I used Strongly Typed Dataset, but this is a clr sql stored procedure and have not found any examples on how to add a .XSD to a stored procedure. The add item option is not available, besides a bunch of typing
My company is tossing around the idea of using the Entity Framework when it comes out with .NET 4. We are currently a VB.NET shop, but have some interest in switching to C#.Is there any major arguments for or against such a move?Does EF with C# hold any advantages in performance, coding ease, etc over VB.NET?
View 10 RepliesI had a post about how to disable monitors, but someone suggested just making it not possible to leave the primary screen. This was obviously a good suggestion, but im not sure how i would accomplish this.
I need to prevent the user from entering the ctrl, alt, delete, escape, and windows key. I also need to prevent the mouse from leaving the primary screen.
My program is a security login system. It requires a username and password to close, and i want to make sure that it cannot close unless the user supplies the correct username and password.
I am a newbie. I have been able to Add new entities where there is a One-To-Many Relation. I am having a problem (don't Know how to do it) adding a new Entity when the relation is using Many-To-Many. In my EDM I have:
[Code]....
I downloaded the VB 2010 Express software, the total files that we included in the download was 15, but it only loaded up 12 of these files. The following downloads did not get loaded as follows:MS Visual Studio 2010 ADO.NET Entity Framework Tools
MS HelpViewe 1.0 x64
I tried reinstalling the downloads that did not using the VB Express 2010 setup, but they do no appear on the list of downloads, only the SP1 for MS SQL Server 2008 Express Server (x64).Do I require the downloads that did not load.
Here are the entities that i have...
Public Class Account
Public Property AccountId As integer
Public Property AccountDescription As String
Public Property Transactions As List(Of Transaction)
End Class
[Code]...
i would like to make it suc that when i do "db.Account.find(1)" for example it also loads in the list of all transactions which have the coresponding AccountId. I'm not too sure what type of relationship this is?? anyway, right now i can do
Dim acct As Account = db.Account.Find(1) acct.Transactions = from ts in db.transactions select ts where ts.AccountId = acct.accountid but i know this is not the correct way, there must be a way to map this out so that entity can just load everything in one shot right?
I am used to using datasets for my projects in terms of data access. I now set myself an easy app to work on in order to learn the entity data framework and how to retrieve & manipulate data.Can anyone guide me through on where to start, what are the advantages of this model, In what scenarios should I choose to use entity framework and what are the things (basis) I should now before starting.My datasets are working fine too. Are there any reasons for me not to stick with that way of accessing data? Or is this something to consider depending on the users of the website (for speed purposes etc.)
View 3 RepliesI'm trying to learn EF in visual basic. I'm struggling with finding any easy to understand simple tutorial of how to do inner joins.
This is the SQL that i'm trying to replicate in EF:
SELECT Quote.LockedDateTime, IncommingQuoteStatus.StatusDesc, Users.FirstName
+ ' ' + Users.LastName AS UserName
FROM Quote
[Code].....
I have some basic expirience in Visual Basic and programming Windows Forms programs. I know now that forms programs are no longer updated by Microsoft and that WPF is the way to go. No to mention the slicker interface you can create. I've also noticed that passing SQL strings to a database is no longer the standard either. It's either Entity Framwork or Linq.
So I am going for a fresh approach. I need to develop a program that will access a sql database and be accessed by about 10 concurrent users within the office. What's the best approach in general? Linq or Entity Framework? Also, could you recommend a book or two for someone who is new to WPF and Entity Framework? I do have some programming expirience, just none with WPF or the new ways of ADO.net 4.
I would like someone to modify the following code to save data to generate the primary key for each record automatically. In the database,the ID column is the primary key and the Is Identity is set Yes.
Try
cmd = New SqlCommand("Insert into StudentDetails.programmes(ID,Programme,Form,AcademicYear,Class) values(@ID,@Programme,@Form,@AcademicYear,@Class)", cn)
cmd.Parameters.AddWithValue("@Programme", txtProgramme.Text)
cmd.Parameters.AddWithValue("@Form", txtForm.Text)
cmd.Parameters.AddWithValue("@AcademicYear", txtAcademicYear.Text)
cmd.Parameters.AddWithValue("@Class", txtClass.Text)
cmd.ExecuteNonQuery()
MessageBox.Show("Record successfully saved", "Saved", MessageBoxButtons.OK, MessageBoxIcon.Information)
I am using MS Visual Basic Express 2010 and trying to generate "ADO.Net Entity Framework" entities from an existing local SQL Server Express database.
Using the "Entity Data Model Wizard" I am asked to configure a connection. Here I prompted to choose a "Data source" and given two options 'Microsoft SQL Server Compact 3.5' and 'Microsoft SQL Server Database File'. I select the second option.
I'm then prompted for connection properties, I have to enter the "Database file name (new or existing)". Here I browse to the SQL server database file of interest (found using Management Studio Express) namely[code]...
I'm currently testing the entity framework 4 for a simple app I wish to build.
how do you save and cancel changes on a record basis? Using the save changes method on the context persists all the changes to the database.
I'm trying to use the Entity Framework to create a complex query and get stuck in the joins. After browsing some of the documentations, I cannot seem to find the correct solution, so maybe someone here can help.
I have a data structure where a family has several family members, each of which can have more than one entry in the income table (on different registration dates) and can have more than one entry in the healthconditions table.
[Code]...
I need to make a if-else statement in the query meaning I only want to add the OpenAmount to ExpectedAmount if the type = Cash, the problem is that it only gives me the cash row not the other row.
[Code]...