各位，搞.net的同志。M$的各种证书，需要搞几个么？

flyspirit

Actually Linq to Sql is only suitable for simple usage. It lacks of many important feature. It is even abandoned by Microsoft itself.

Microsoft put hope on Entity Framework, but EF in .Net 3.5 is immature. In.NET 4 it might be improved a lot. But .NET 4 hasn't been released.

All ORM framework have limitations. They only suitable for medium size database. For large DB requires high performance, you have to write native SQL.

澳贼

原帖由 flyspirit 于 2010-3-10 15:51 发表
Actually Linq to Sql is only suitable for simple usage. It lacks of many important feature. It is even abandoned by Microsoft itself.

Microsoft put hope on Entity Framework, but EF in .Net 3.5 is i ...

所以说，只用三年以上的成熟技术

Gelen

各种MS证，请站内短信我

runxi328

原帖由 澳贼 于 2010-3-10 15:54 发表


所以说，只用三年以上的成熟技术

yes, i like .net 2.0 (ado.net), pretty much old school throu

澳贼

原帖由 runxi328 于 2010-3-10 15:57 发表


yes, i like .net 2.0 (ado.net), pretty much old school throu

actually, .net 3.0 and above just names for marketing. all functions can be done by 2.0

中间人

#31，请举几个例子，linq to sql相较sql后者sp所缺乏的东西，讨论讨论也好。

另外，如果说 linq to sql 仅仅是 handy，有失偏颇。

澳贼

原帖由 Gelen 于 2010-3-10 15:55 发表
各种MS证，请站内短信我

你是办证的？？

中间人

Actually Linq to Sql is only suitable for simple usage. It lacks of many important feature. It is even abandoned by Microsoft itself.

abandoned by Microsoft itself 这个传说流传确实很广。随便google一下linq to sql在vs2010里的特性吧。当然EF可能慢慢替代它。

runxi328

原帖由 澳贼 于 2010-3-10 15:59 发表


actually, .net 3.0 and above just names for marketing. all functions can be done by 2.0

u r right.

.net 3.0 is service pack 1 of .net 2.0, .net 3.5 is service pack 2.

中间人

所以说，只用三年以上的成熟技术

这么说你还没有用3.5，这边4.0都出了。

flyspirit

原帖由 中间人 于 2010-3-10 16:02 发表
#31，请举几个例子，linq to sql相较sql后者sp所缺乏的东西，讨论讨论也好。

另外，如果说 linq to sql 仅仅是 handy，有失偏颇。

You can checkout this post http://www.thinqlinq.com/default ... ments-for-2010.aspx

As the post said, the new LINQ to SQL contains mainly bug fixes but not many new features

If you compare Linq to SQL with NHibernate(Hibernate for .NET), you will find it lacks of many features. Such as object relationships, lasy loading, caching and support for Class Hierarchy.

澳贼

原帖由 中间人 于 2010-3-10 16:19 发表


这么说你还没有用3.5，这边4.0都出了。

用了点LINQ, 毕竟方便

flyspirit

原帖由 runxi328 于 2010-3-10 16:17 发表


u r right.

.net 3.0 is service pack 1 of .net 2.0, .net 3.5 is service pack 2.

I have other thoughts. Indeed I think .NET 3.0 has much more feature than 2.0. For example, WCF, WPF and WWF.
These 3 frameworks are very important feature improvement. If you look at the job ads of .NET now, nearly all of them at least one of them.

In .NET 3.5, I reckon the major improvement is the introduction of LINQ. This term is appeared on almost all relevant job ads as well.

[ 本帖最后由 flyspirit 于 2010-3-10 16:52 编辑 ]

runxi328

i think wcf/wpf/wf are quite independent framework. there are not core part of .net 3.5, rather, they are surrounding parts.

yes, u r rite, everyone was excited about 3.5, but how many pple actually use wcf/wpf/wf? as far as i know, numbers are quite limited, especially wpf/wf.

aside from linq to sql, i still don't see any of linq (to object,to xml,to dataset...ect) is widely adopted by asp.net industry.

correct me if i'm wrong, i might too much focus on our own product, thus, losing bigger picture of tech trend.

中间人

object relationships, lasy loading, caching and support for Class Hierarchy ...

没用过NHibernate。根据字面意思：object relationships 都有，lasy loading = delayed execution， cache = Linq to entity，不明白你support for Class Hierarchy具体指什么， 继承吗？或者partial class？

flyspirit

It doesn't matter if Ws are core parts or not. You can not use them upon .NET 2.0. They require at least 3.0.

I reckon WCF and WPF are widely used. If you use lots of Web Service, which is the basic of SOA architecture, you probably need deal with WCF. WPF is the future of GUI development and is fully supported by MS. I don't know the percentage yet, but in blogs, job ads, discussion groups, they are hot techs.

LINQ is more popular. It can be used against different data source. For example, it can be used against array, list, collection and perform different tasks like sort, join, filter .etc. It is very easy to use compared to traditional ways and benefit is high productivity.

flyspirit

原帖由 中间人 于 2010-3-10 17:25 发表


没用过NHibernate。根据字面意思：object relationships 都有，lasy loading = delayed execution， cache = Linq to entity，不明白你support for Class Hierarchy具体指什么， 继承吗？或者partial class？

for example, if I have two tables, one category table and one product table. Product table has a column named product.categoryID which is FK of category. In Linq to SQl, if you have a category object, and want to retreive all its products, you have to write code like:

var products = from p in t_product where p.categoryId == category.Id select p

In NHibernate, you can do this: products = category.products

You see the difference?

In a more complex senario, say, each products have a list of parts. In LINQ to SQL, you have to write nest query to access "parts" collection. However, in NH, you write Category.Products.Parts

Another doubt I have is how you create the relations in the designer if you have a hundred tables?

The cache is not linq to entity, they are different concepts.

"Class Hierarchy" means, if you have hierarchy in your table structure, you can mapping it to a set of classes and keeps the hierarchy. More important, you can access the properties in super class from subclass. Since NH can find out where the original column is and go to the super table accordingly.

中间人

楼上，除了"Class Hierarchy" (which covered by EF in 4.0), Linq to sql can do exactlly the same thing。
我觉得如果你不了解一样东西，先深入的用用，再评价比较好。

以下代码是northwind数据库，category和product表都加入到diagram，run没有问题。
var a = from c in db.Categories where c.CategoryID == 1 select c.Products;
var b = db.Categories.First(x => x.CategoryID == 1).Products;

[ 本帖最后由 中间人 于 2010-3-10 21:59 编辑 ]

澳贼

原帖由 runxi328 于 2010-3-10 17:13 发表
i think wcf/wpf/wf are quite independent framework. there are not core part of .net 3.5, rather, they are surrounding parts.

yes, u r rite, everyone was excited about 3.5, but how many pple actuall ...

完全同意

澳贼

原帖由 flyspirit 于 2010-3-10 18:25 发表
It doesn't matter if Ws are core parts or not. You can not use them upon .NET 2.0. They require at least 3.0.

I reckon WCF and WPF are widely used. If you use lots of Web Service, which is the basi ...

这位大虾，能深入地说说SOA 么？？ 很多人用这个词，可我问他们啥意思时，没人能说出所以然。

中间人

这位大虾，能深入地说说SOA 么？？ 很多人用这个词，可我问他们啥意思时，没人能说出所以然。

你常面试别人啊？

澳贼

原帖由 中间人 于 2010-3-10 21:26 发表


你常面试别人啊？

不常，就一次。 很多人的简历都写上，Strong SOA . 可一问，基本都是给我编。

中间人

不常，就一次。 很多人的简历都写上，Strong SOA . 可一问，基本都是给我编。

咋编的？基本上如果人家的系统后端完全建立在web service或者wcf之上，那就可称为SOA了呀。

澳贼

原帖由 中间人 于 2010-3-10 21:34 发表


咋编的？基本上如果人家的系统后端完全建立在web service或者wcf之上，那就可称为SOA了呀。

可大可小 http://en.wikipedia.org/wiki/Service-oriented_architecture

[ 本帖最后由 澳贼 于 2010-3-10 21:39 编辑 ]

澳贼

yet there is considerable confusion and hype concerning what service-orientation is and what it means. To make matters worse, most of the vendors in this space equate their definition of service-orientation with their products and services. The vendors (Microsoft included) add to the confusion by equating service-orientation with high-end Enterprise applications

flyspirit

原帖由 中间人 于 2010-3-10 21:01 发表
楼上，除了"Class Hierarchy" (which covered by EF in 4.0), Linq to sql can do exactlly the same thing。
我觉得如果你不了解一样东西，先深入的用用，再评价比较好。

以下代码是northwind数据库，category和 ...

To be honest, I don't have much interest in LINQ to SQL since it's abandoned by MS itself. Obviously, EF is MS's hope for ORM. But anyway, I appreciate that you correct my mistake.

Can you confirm regarding object relationship, does LINQ to SQL support many to many relation?

Another question in my mind is, how can you cope with a large database with lots of tables, as per example, a hundred? It will be a nightmare if you use the designer in this senario.

ATO

我个人体会吧，直接买假证就可以，靠读很浪费，读的这些我都懂。

flyspirit

原帖由 澳贼 于 2010-3-10 21:22 发表


这位大虾，能深入地说说SOA 么？？ 很多人用这个词，可我问他们啥意思时，没人能说出所以然。

Although our system is based on WCF, I'm not sure if it coincident with SOA standards. I haven't learned SOA systematically so just talk some feelings here.

To make it simple, start from an example.
Imaging at client side, you need get a product list, so you call a method GetProducctList(). In old ways, the method is likely to be in an assembly.
In Webservice world, you still call GetProductList(). But this time it is a service hosted in another machine. The benefits of web service are:
scalability: you can add more server to provide GetProductList web service.
accessibility Since based on http, it can be access anywhere in intranet and internet
platform independent, web service developed by java can be used by C# client for example

Web service shows some advantages here. Based on this SOA is developed. It contains several tenets and consequently a bunch of best practices and patterns. For example, granularity of service, versionning,  relationship between services, security. etc.

中间人

Can you confirm regarding object relationship, does LINQ to SQL support many to many relation?
Another question in my mind is, how can you cope with a large database with lots of tables, as per example, a hundred? It will be a nightmare if you use the designer in this senario....

Linq to sql does support many to many relationship.
With a large database, you can start using linq to sql based on the business logic unit, step by step, then each time you will be only dealing with limited tables. BTW if there is a database with 100 tables, then the first thing we should do is redesign the database.

Again, MS doesn't abandon Linq to sql. It may be replaced by EF in a period of time, but getting more familiar with linq to sql will make it easier to pick up EF. You may use some similar skills right now, nhiberbnate for example, but it is not a excuse to have prejudices on the other skills.

Any one have question about Linq to sql or Linq to entity, welcome, we can have a discussion here. :)

flyspirit

It's not maybe, It's definetly will be replaced by EF. If a tech will be replaced by another, isn't that means it will be abandoned? How easy is to migrate a system from LINQ to SQL to EF, I think you don't know the answer yet.

Dealing with 100 tables is not unusal for a large system. And in most cases it's not practical to redesgn it, since you either find they are neccessory or you don't have resources.

The ways you suggest  to use LINQ to SQL against large db is not realistic. It's quite clear that LINQ to SQL only suitable for simple databse structure. There are many posts confirmed this.