We would like to perform something like this
string strCondition = "FirstName=='abc'"
from p in People.Where(strCondition) select p
In our architecture we are usign both Linq-Sql as well Linq-Entity. So please give some thoughts wehter it is possible or not and is there any way to perform this?
I've added the Dynamic.cs file to my project and have set it's Build Action = Compile in order to get the System.Linq.Dynamic namespace.
However, when I try to use any of the new code I am getting an ambiguous call error; see below.
[Code]....
I have this query for getting data through Entity Framework, which works today. Thing is, i want to create the query dynamically, i.e build it up in blocks, but i can't figure out how exactly to do it. I believe if i can somehow save one of the values that i retrieve in the beginning i can do it, but now i retrieve it twice (probably a bit slow as well? Unless the compiler fixes it before quering). Makes sense? Here is the LINQ:
[code]....
I.e based on if various variables have values.
I have the code below could to rewrite from LINq to SQL to Linq to Entity.
[code].....
The gist of the problem is that we have an alumni table (one record per person) and also a couple of other tables (one to many) that have degree info and interest info. In a search screen in our app you can search for criteria that spans all three tables (there are actually more fields and tables than shown in the example below but I am trying to keep it simple).
The code below works (properly returns people without degrees for example) but still feels a little clunky or over-engineered to me. Are there easier ways to do this? NOTE: I have been through quite a few iterations/approaches to making the correct data be returned.
[code]....
i have function
public Menu Details(int? id)
{
return _dataContext.Menu.Include("ChildMenu").FirstOrDefault(m => m.MenuId == id);
}
now i need to add condition to child list ChildMenu something like fieldname=id. how can i do it?
There is my code, I'm a newbie with linq. I don't know really how to link my two dropdownlist using linq:
[Code]....
I have a list of customer Id's as the result of a Linq Query named "localCustomers" which contains 100 or so Customer ID's.I'm would like use this list to query and access customers' info on the whole group. Been searching on how to do this but no luck. It's easy enough with one customer ID, but how do I do it with an arrayList as the parameter? Here's my latest attempt but it's not working.
[Code]....
I'm new on LINQ and I'm searching the best way to do this:
I have an object client that has a list of subscriptions. Subcription has a boolean attribute "Active". Now I want load only the clients with list > 0 and subscription active.
The question is: If a client has 3 subscriptions, but only 2 are active, how can I load only the latters ? I tried in this way:
[Code]....
The query selects clients that has at least one subscription active, but viewing the results, it loads also subscriptions not active of the same client.
Whats the best method to use with MVC? Entity Framework or LINQ to SQL?
View 4 RepliesIm working on a greenfield project and have to make a decision on the technology we'll use for the data access layer. Ive used LINQ to SQL for a few years and am happy and comfortable with this, but now with entity framework available this is another method to consider. Are there any pitfalls using entity framework as opposed to LINQ to SQL ? Ive read that there are performance issues with entity framework, is this true? Id really like to get an overall feel for using one method over the other, anyone have any thoughts/comments/recomendations?
View 1 RepliesI'm trying to learn MVC. Now I wonder whats the different between entity framework and LINQ TO SQL? Wich is the best to use and why?
View 19 RepliesIm new to development for the windows server platform. Can someone tell me the difference between Linq to SQL and EF4?
View 2 RepliesType 'System.Data.Linq.ChangeTracker+StandardChangeTracker' in Assembly 'System.Data.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' is not marked as serializable
have read all threads but still cant solve the error. I can do insert update and delete but dont know where exactly the error occurs and how??
How can I update an existing LINQ entity? This code gives me: "Cannot insert an entity that already exists."
Any better practises on updating/inserting with linq?
foreach (ListViewItem lvi in lvStudents.Items)
{
HiddenField hfStudentID = lvi.FindControl("hfID") as HiddenField;
CheckBox cbPresent = lvi.FindControl("mycb") as CheckBox;
int sInt = Int32.Parse(hfStudentID.Value);
dc = new DataClassesSODataContext();//I renewed the dc to make sure that wasn't the problem?
var currStudent = dc.students.Single(x => x.studentID == sInt);
grade g = dc.grades.Single(x => x.subjectID == subjID || x.studentID == sInt);
if (g == null)
{
g = new grade();
g.subject = dc.subjects.Single(x => x.subjectID == subjID);
g.student = currStudent;
g.present = cbPresent.Checked;
dc.grades.InsertOnSubmit(g);
} else
{
g.present = cbPresent.Checked;
dc.grades.Attach(g, true);//I tried both attaching and inserting
}
}
dc.SubmitChanges();
what is diffrence between Entity Framework and LINQ to SQL i cant yet find a good blog on this i have read that in LINQ to SQL only one to one mapping is possible but Entity Framework allowes many , is it right? if so i dont understand this
View 3 RepliesCould any one explain me which ORM is best?
View 3 RepliesI have a new project where I want to use MVC (I will be learning as I code), and I have never used linq or entity (or mvc). Which should I use? Does it matter? I will be having a lot of different databases, from Oracle to FoxPro.
View 6 RepliesHi guys I need to rewrite the sql query below using Linq to entity. Unfortunately I don't have a lot of experience of using Linq.
With TempTableName AS
(SELECT [ColumnName],
[ColumnName2],
[ColumnName3],
[ColumnName4],
ROW_NUMBER() OVER (order by ColumnName desc) as RowNumber from TableName )
SELECT
[ColumnName],
[ColumnName2],
[ColumnName3],
[ColumnName4]
FROM TempTableName WHERE ROWNUMBER
Between 10 and 100
i have a database with 4 table aspnet_Users, Forum, Topic, Post thay are related:
aspnet_Users with Topic by UserId
Forum with Topic by ForumId
Topic with Post by TopicId
i created a linq to get data from Database like:
[Code]....
now i need to get also how meny post are in a topic but i don't know how to write the querry.
select * from MyTable select "MonthName"= case when datepart(month,date1) =1 then 'January' when datepart(month,date1) =2 then 'February' end , count(*) as CountByMonth from venkat group by datepart(month,date1)
View 1 RepliesI am using the following LINQ to entity to get data from my db.
It should return only one row. So i want to be able to get the first row in the set and not have to go through a foreach.
I would also like to check and make sure it is only returning one row, if it returns multiple i need to throw an exception
[Code]....
I worked with LINQ to SQL to insert and delete the data,but i want to use LINQ TO ENTITY to insert the data but i know LINQ to ENTITY is used for querying the database.I have searched the code for inserting records but i dint get any.
View 7 RepliesI am selecting some products from database and would like to show them in client's grid using WCF. Problem is I don't know how to pass selected collection to the client since my method can't return that data type.
My method:
public class Service1 : IService1
{
public ProductData GetData(int value)
{
using( NorthwindEntities NWEntities = new NorthwindEntities()){
[Code]....
When do I need (/ best practice) to use views and stored procedures in my database when using linq with the entity framework?
View 8 Replies
