What are the pro's and con's of using "Linq to SQL" and core ADO.NET technology for access databases?
Advantage
No need to create business objects dbml files will do for you
No need to worry about writing queries because linq2sql convert your statment in efficient queries
Important is Lazy Loading of related objects
Disadvantage
Disconnect linq is not supported i.e you cannot deatch you objects form DataContext object. for more detail : Most efficient way to update with LINQ to SQL
I have the same view point as this post, I've yet to find any major disadvantages of Linq.
I have built a number or application and websites using Linq and found it to be extremlly simple to use
http://forums.asp.net/t/1520157.aspx
comment by BoogleC
Regards
Sp
Id also be carefull about how you write you LINQ statement. Sometimes its better to compile your Linq rather than not as every single run of the Linq query is fully parsed every time it happens. See below linq
http://www.codinghorror.com/blog/2010/03/compiled-or-bust.html
I wouldn't recommend LINQ to SQL at all as it is effectively dead (you don't want to be writing legacy code, right?). Microsoft is no longer developing it and they recommend using the Entity Framework instead (see here), however, if you are interested in using an ORM, I would strongly recommend looking at NHibernate.
Related
We have some legacy code that uses Linq to SQL as the ORM. We'd like to migrate this logic to .Net Core so that we can house it on a linux server. As far as I can tell, L2S is not included in .Net Core.
What is the migration path of least resistance?
If you used L2S because EF is inefficient at using Skip and Take for fetching large results as chunks, then your best bet is Dapper. Get yourself a copy of LINQPad and use it to get the generated SQL for each of your LINQ expressions.
L2S wraps some bizarre SQL around the actual query to use SQL's rownumber function to implement skip and take. If you are using the latest version of SQL Server then you don't need this because TSQL now has clauses equivalent to skip and take. This is handy if you are writing SQL directly and produces comprehensible SQL that won't induce WTF in those who follow, but the LINQ way works on all versions of SQL Server.
Then use this SQL with Dapper, which will do the ORM part for you. It also has proper support for type mapping parameters similar to L2S so you can avoid building SQL strings and injection vulnerabilities.
If you want all the smarts for constructing object graphs with FK values implied by collection membership then you're out of luck, you'll have to code it by hand.
update 2018-05-11
EF is less horrible than it used to be. EF Core is simpler than EF while retaining many of the benefits. I am currently using EF Core on a project at work and it's not the disaster EF once was.
I did have to help with an outer join. Left to its own devices, LINQ fetched the inner part and then for each inner row ran a separate query for its outer portion.
I fixed this by explicitly fetching the inner part and constructing a keyset as an array of int. Another LINQ statement fetched all of the outer rows exploiting the fact that Array.Contains maps to IN which uses indexes. Then I materialised both parts using ToArray() and used LINQ to join them in memory. This brought execution time down from ten minutes to 300ms.
You shouldn't have to do this; L2S wouldn't have cocked it up in the first place. But at least there's a straightforward general solution.
A shortcoming of my solution is that it is not well adapted to progressive fetch.
update 2020-06-12
Dapper can return dynamic results. I find this is a good bridge between SQL and C#. The columns and their names are governed by the SQL. This can be a little fragile since C# is case sensitive and SQL isn't, but with the SQL in your code you can at least see what it is and fix it.
More to the point, you can use LINQ directly on these dynamic results.
DevArt's LinqConnect now support .NET Core as of May 2017:
https://www.devart.com/news/2017/net-core-support.html
It's a drop in replacement for Linq To Sql and it even dislocates you from MS SQL Server if you so wish!
If you are rewriting legacy code to .NET Core, this will take some effort to being with.
And for L2S, you will probably need to rewrite this into modern queries using Entity Framework Core. It might make your life easier generating entities from database though, see Reverse engineer your model.
This would be the recommended way, however I am not sure if it's the easiest one in your case.
What are the advantages of EF4 and under what circumstances is it preferred over LINQ to SQL?
LINQ to SQL will have no more future development. So EF is the way to go in the future.
Entity Framework vs LINQ to SQL (this should explain what you want to know)
Well, two of the major differences are:
1) EF can target multiple database engines, including Oracle and MySQL. Not just MS SQL Server.
2) You can do so-called "code first" schema development. Basically you create your object model, and along with some hints, EF will generate the schema for you.
Seems to me that Linq to Sql is great for rapid prototyping and simple CRUD scenarios. Anything more advanced or enterprisey would use EF4. (Or at least that's what MS would like us to believe :) I've had good luck with Linq to SQL in production, for what it's worth.
EF4 basically adds a whole bunch of OO-ness to the mapping that isn't present in LINQ-to-SQL, such as rich object inheritance models. My own take on it is that none of that is necessary for good design, and I have yet to come across a single scenario in my own work that warrants the added complexity EF4 brings to the table.
Having said that, Microsoft has deprecated LINQ-to-SQL and will not continue developing it, so it will eventually fall behind EF4 in capability and efficiency (if it hasn't already). So the pragmatic choice is simple: go EF4.
After trying both and spending over one weeks porting a project from linq to sql, I can say that I really prefer Linq to SQL. The main reason for this is that EF is more restrictive on what functions you can use in LINQ queries. In EF I had to cast my linq expressions to a list to be able to manipulate them any further. Sorry for not being able to remember any example, it's been a few months since I did this...
One of the really big plus sides for EF, is the ease of use in connection with WCF Data Services. Very handy if you are developing a web site that should have an RESTful API.
Also, even though Linq to SQL is quite mature, it is indeed a dying technology. It won't get any significant updates, that makes it harder to commit to Linq To SQL for a new project.
We're working on an ASP.NET web application with C# code behind. The database is MySQL 5.1 using InnoDB. The data access layer uses ADO.NET to call stored procedures and then builds various data structures out of the result sets (no object mapping). This works fine, but it is a little verbose.
Not surprisingly, we made some mistakes when designing the first version of our data model, but the experience has made us smarter and we decided to refactor the data model. We don't have to change our data access layer, but we are considering our options for that as well.
It's been difficult for us to ignore the popularity of ORM tools these days; we feel like we are way behind or something for not being familiar with them. Not only that, but we have already designed an object model that nicely describes our data model. The main ORM tools we would consider are NHibernate, ADO.NET Entity Framework, and LINQ to SQL. We would prefer LINQ to SQL because we have read (on S.O.) that it is more light weight than full ORM tools.
We think one drawback to using an ORM tool is the learning curve, but we can already see how using LINQ could reduce the amount of code we will have to write, which could save us time in the long run. However, we are using MySQL, not SQL Server.
So my question is, would DBLinq work well enough for a production system? Or, is LINQ to SQL a compeling enough reason for us to make the move to SQL Server 2008? Incedentally, I'd prefer to use SQL Server over MySQL, but cost is the obvious drawback. After 3 years on BizSpark, we'd be on the hook for $6K. Or, should we consider other ORM tools instead? Or, should we just ignore the hype and not use an ORM tool, but maybe take advantage of LINQ to DataSet?
I searched S.O. for info on DBLinq, but only found 17 questions with the DBLinq tag, so it doesn't appear to be popular.
EDIT
Looks at though dotConnect for MySQL has support for LINQ, so that's another option.
Can anyone speak to how well that driver works for writing LINQ queries?
Check bl-toolkit. It's free, very fast and has great LINQ support. Newest addition are T4 templates for generating your data model from database.
I'll just put it out there that I'm new to LINQ to SQL. Hell, i'm relatively new to programming in general.
Anyways, I would like to learn and use LINQ to SQL to a project that was built using .NET 2.0 Framework. The project uses stored procedures to access the database (there's no dynamic SQL queries on the front end servers). LINQ to SQL seems a great alternative to stored procs but to introduce it to my project would break the principle of 'Separation of Concern'. Would it be best to not break this principles and just write more stored procedures when needed? Or is there a way to use LINQ to SQL without breaking the principle?
I generally find it hard to add new technology and tools in legacy projects without breaking the consistencies in projects.
Having code which interacts with the database server through SQL instead of through stored procedures is not a violation of separation of concerns, as long as that code is well modularized and the LINQ to SQL part cares only about data entry/retrieval and is not intermingled with other tasks (concerns). LINQ to SQL usage does not break any principle
Now, modifying code not to use SPs when it has been coded that way from the beginning will probably not be a small task and there might not be any real benefit in the end other than you learning LINQ to SQL.
Actually, LINQ to SQL helps a great deal with SoC. It separates the fact that you are using SQL from your domain objects even more than a traditional sproc-based DAL. Having a bunch of methods which call into stored procedures is a poor-man's attempt at the same thing - minimizing but not eliminating contact points between the DAL and the business logic. The LINQ to SQL library becomes your DAL, and you're free to manipulate a bunch of stupid objects with no direct ties to any data backing - with the added benefit of being able to express directly against your domain objects using LINQ expressions, instead of relying on the pre-determined permutations of stored procs.
If the project is a large one and uses many sprocs then it is not a smart idea to replace it's sprocs with LINQ. The reasons should be obvious why it is not prudent to do so. However, moving forward, this in no wise means you shouldn't implement a layer for LINQ. This is what I have done with some of my larger legacy apps. Implementing and using LINQ is well worth the effort, but it is not worth the effort (nor worth the risk) to rewrite old sprocs to use LINQ.
Im on to design my Data Access for a new solution i create. That solution though contains Compact Framework Device Application and libraries besides Desktop. All .NET 3.5. Desktop will handle all Data Access basically. I need the Data Objects to have in CF too, Desktop will communicate with SQL and then with Mobile and give the appropriate data...
I love LINQ, and more i love LINQ 2 SQL. There is a lot of hype out there and i don't buy internal Microsoft politics about recommending EF. For now EF is too heavy and too complex for someone to choose it besides it still evolving and EF 4 will have major changes when it comes in a few months. But i cant wait for months to create a project as every developer in here, i want something now! After that said i want to use LINQ 2 SQL, my problem is that i cant just copy the generated dbml and use the generated classes. I don't need the DataContext cause i don't intend to use CRUD or any operations on a database with the Mobile App. i Just want the Objects. Anyone ever came in a situation like this? The whole point is not to write all classes representing the tables by hand. Cause i need them for further LINQ to Objects manipulation.
Basically an ORM supporting CF would do the job! But i don't know any incompatibilities i would meet.
I've been able to modify SubSonic 3.0, the db4o/Mainsoft port of System.Linq.Expressions from the Mono project after adding the missing Queryable sources, and Matt Warren's IQToolkit on Codeplex to provide a L2S equivalent on the CF.
This is about what it takes, though, since Linq expression trees are not supported on .Net CF 3.5.
I was able to use the DbEntityProvider/DbEntitySession and AttributeMapping/XMLMapping imported to Subsonic from IQToolkit to provide better entity and table-to-class mapping support.
L2S works great with the compact framework. You can't use the drag-and-drop designer, though. You'll need to run SQLMetal.exe yourself to generate the classes for you.
SQLMetal.exe: http://msdn.microsoft.com/en-us/library/bb386987.aspx
Example with Northwind compact: http://blogs.msdn.com/sqlservercompact/archive/2007/08/21/linq-with-sql-server-compact-a-ka-dlinq-over-sql-ce.aspx
Another example, with lots of pictures: http://pietschsoft.com/post/2009/01/Using-LINQ-to-SQL-with-SQL-Server-Compact-Edition.aspx
You could use DevExpress persistent objects (XPO) on compact framework. I have used it before but found it to be somewhat slow for my purpose (data collection application).
The reason that you cannot find much of this on the compact framework is that speed is usually so important for device apps, that data access code is usually done manually.
I don't know if you can create objects from an already existing database with XPO.
This is one good option generating from dbml file plain POCO classes working with LINQ 2 SQL. Not tested yet but seems promised.
http://www.codeplex.com/ULinqGen
Have you checked out Kea - Linq for Sql Compact & Compact Framework?
http://kea.codeplex.com/