与技术和数据库的推进它在编程part.成为了检索数据的一个巨大挑战快速地和以较少负担。

它变得明显下个大挑战在编程的技术是减少没有使用OO技术当地被定义访问的和集成的信息的复杂。 non-OO信息的二个共源极是关系数据库和XML。

主要好处 微软？s LINQ项目 是他们接受的一般方法，因为他们集成了查询语言不问任何具体部分。语言集成询问可以使用以是能退回IENUMERABLE的XML，数据库或者任何。

这能解释的一个小讲解。 这特别地是为爱做到porgamming的我的读者。

这是我在doc发现可能表达LINQ的力量和真正地做程序员小点网微笑的小片。

使用系统; 使用System.Query;
使用System.Collections.Generic;
类app {
静止空扼要() {
串起[]命名= {？室息？ ？康纳？ ？直率？ ？Everett ？ ？阿尔伯特？ ？乔治？ ？哈里斯？ ？大卫？ };

IEnumerable expr =从s在名字
那里(s.Length == 5 orderby s)
选择s.ToUpper ();
foreach (串项目在expr)
Console.WriteLine (项目);

}

}

Linq怎么与XML一起使用？

询问建筑学的延伸性用于LINQ项目提供运作在XML和SQL数据的实施。

沉重使用的Xpath和Xquery在主人编程语言。 这再一个代码片断为显示多么容易它是工作与是的LINQX (是什么XML要求它？s)

标准方式完成如下：

XmlDocument doc =新的XmlDocument ();
XmlElement名字= doc.CreateElement (”名字”);
name.InnerText = “帕特里克Hines”;
XmlElement phone1 = doc.CreateElement (”电话”);
phone1.SetAttribute (”类型”， “家庭”);
XmlElement phone2 = doc.CreateElement (”电话”);
phone2.SetAttribute (”类型”， “工作”);
XmlElement street1 = doc.CreateElement (” street1 ″);
XmlElement市= doc.CreateElement (”城市”);
city.InnerText = “Mercer海岛”;
XmlElement状态= doc.CreateElement (”状态”);
state.InnerText = “WA”;
XmlElement邮政= doc.CreateElement (”邮政”);
postal.InnerText = “68042 ″;
XmlElement地址= doc.CreateElement (”地址”);
address.AppendChild (street1);
address.AppendChild (城市);
address.AppendChild (状态);
address.AppendChild (邮政);
XmlElement联络= doc.CreateElement (”联络”);
contact.AppendChild (名字);
contact.AppendChild (phone1);
contact.AppendChild (phone2);
contact.AppendChild (地址);
XmlElement接触= doc.CreateElement (”联络”);
contacts.AppendChild (联络);
doc.AppendChild (联络);

If we see it little closer the above code , This style of coding provides few clues to the structure of the XML tree. but with LINQX it becomes more of what they as functional construct.Here is what how u code the same with LINQX?.

XElement contacts = new XElement
(”contacts”,new XElement(”contact”,
new XElement(”name”, “Patrick Hines”),
new XElement(”phone”, “206-555-0144″,
new XAttribute(”type”, “home”))
,new XElement(”phone”, “425-555-0145″,new XAttribute(”type”, “work”)),
new XElement(”address”,new XElement(”street1″, “123 Main t”),
new XElement(”city”, “Mercer Island”),
new XElement(”state”, “WA”),new XElement(”postal”,”6843″)

This is so simple no hassles at all.

How LINQ works with database

Yup its done By Microsoft again under LINQD(thats LINQ for database). The query operators over relational data (DLinq) build on the integration of SQL-based schema definitions into the CLR type system.

This integration provides strong typing over relational data while retaining the expressive power of the relational model and the performance of query evaluation directly in the underlying store.

What we kneed to know is the structure of database table we want to deal with it and create a class exactly having private variables as columns of the underlying table say may be like save that easy.Thus in simple way we create an object of the row of that table in memory and do operation on that and ask somebody to save it.Moreover we can ask for a collection of those rows fo get more than one record and do a query on it..isnt that great no hassles of database sql.

1. Create an entity class with mapping to database table like this:-

[Table(Name="Customers")]
public class Customer
{
[Column (Id=true)]
public string CustomerID;
private string _City;
[Column(Storage = "_City")]
public string City
{
get { return this._City; }
set { this._City = value; }}}

2.Create a Data context to load from database

static void Main(string[] args){
// Use a standard connection string
DataContext db = new DataContext(
@?C:Program FilesLINQ PreviewDatanorthwnd.mdf?);
// Get a typed table to run queries
Table Customers = db.GetTable();

3.Query what you get?.

// Attach the log showing generated SQL to console
// This is only for debugging / understanding the working of DLinq
db.Log = Console.Out;
// Query for customers in London
var custs =
from c in Customers
where c.City == “London”
select c;
}

Thats how it works with database?.easy isn’t it?This Technology will come with DotNet Framework 3.0 and with C#3.0 and VB 9. I havent covered every thing but just a quick glance which can get grasping things faster. If you want to read more on it see the Microsoft?s LINQ Project

Related : Linq provider for Twitter API

Tags: dot-net-framework3, Microsoft, msdn