以一種統一的方式操作各種數據源，減少數據訪問的複雜性.類似Hibernate的對象級訪問，不考慮後臺數據庫的類型等等。自動生成各種類型的查詢數據源語言。
查詢句法
查詢句法是使用標準的 LINQ 查詢運算符來表達查詢時一個方便的聲明式簡化寫法。該句法能在代碼裏表達查詢時增進可讀性和簡潔性，讀起來容易，也容易讓人寫對。 Visual Studio 對查詢句法提供了完整的智能感應和編譯時檢查支持。編譯器在底層把查詢句法的表達式翻譯成明確的方法調用代碼，代碼通過新的擴展方法和 Lambda 表達式語言特性來實現。
var selectperson = from p in persons where p.age >= 20 select p.username.ToUpper();
foreach(var p in selectperson)
Console.WriteLine(p);
上面的查詢句法等價於下面的代碼：
查詢方法
var selectperson = persons.Where(p=>p.age>=20).Select(p=>p.username.ToUpper());
DataContext
使用 DataContext 類型把實體類和數據庫中的數據進行關聯。
強類型 DataContext
public partial class NorthwindDataContext : DataContext
{
public Table<Customer> Customers;
public NorthwindDataContext(IDbConnection connection) : base(connection) { }
public NorthwindDataContext(string connection) : base(connection) { }
}
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@font-face
{font-family:"Cambria Math";
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mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1107304683 0 0 159 0;}
@font-face
{font-family:ˎ̥;
panose-1:0 0 0 0 0 0 0 0 0 0;
mso-font-alt:"Times New Roman";
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-format:other;
mso-font-pitch:auto;
mso-font-signature:0 0 0 0 0 0;}
@font-face
{font-family:"/@SimSun";
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mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-unhide:no;
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mso-pagination:none;
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font-family:"Times New Roman","serif";
mso-fareast-font-family:SimSun;
mso-font-kerning:1.0pt;
mso-fareast-language:ZH-CN;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
font-size:10.0pt;
mso-ansi-font-size:10.0pt;
mso-bidi-font-size:10.0pt;
mso-ascii-font-family:"Times New Roman";
mso-fareast-font-family:SimSun;
mso-hansi-font-family:"Times New Roman";
mso-font-kerning:0pt;}
/* Page Definitions */
@page
{mso-page-border-surround-header:no;
mso-page-border-surround-footer:no;}
@page Section1
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margin:72.0pt 90.0pt 72.0pt 90.0pt;
mso-header-margin:36.0pt;
mso-footer-margin:36.0pt;
mso-paper-source:0;}
div.Section1
{page:Section1;}
-->
NorthwindDataContext ctx = new NorthwindDataContext("server=xxx;database=Northwind;uid=xxx;pwd=xxx");
GridView1.DataSource = from c in ctx.Customers where c.CustomerID.StartsWith("A") select new {
顧客
ID = c.CustomerID,
顧客名
= c.Name,
城市
= c.City };
GridView1.DataBind();
1.日誌功能
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@font-face
{font-family:"Cambria Math";
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mso-generic-font-family:roman;
mso-font-pitch:variable;
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@font-face
{font-family:ˎ̥;
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mso-font-alt:"Times New Roman";
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-format:other;
mso-font-pitch:auto;
mso-font-signature:0 0 0 0 0 0;}
@font-face
{font-family:"/@SimSun";
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mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
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{mso-style-unhide:no;
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text-justify:inter-ideograph;
mso-pagination:none;
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mso-bidi-font-size:12.0pt;
font-family:"Times New Roman","serif";
mso-fareast-font-family:SimSun;
mso-font-kerning:1.0pt;
mso-fareast-language:ZH-CN;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
font-size:10.0pt;
mso-ansi-font-size:10.0pt;
mso-bidi-font-size:10.0pt;
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mso-fareast-font-family:SimSun;
mso-hansi-font-family:"Times New Roman";
mso-font-kerning:0pt;}
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@page
{mso-page-border-surround-header:no;
mso-page-border-surround-footer:no;}
@page Section1
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mso-header-margin:36.0pt;
mso-footer-margin:36.0pt;
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div.Section1
{page:Section1;}
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using System.IO;
NorthwindDataContext ctx = new NorthwindDataContext("server=xxx;database=Northwind;uid=xxx;pwd=xxx");
StreamWriter sw = new StreamWriter(Server.MapPath("log.txt"), true); // Append
ctx.Log = sw
;
GridView1.DataSource = from c in ctx.Customers where c.CustomerID.StartsWith("A") select new {
顧客
ID = c.CustomerID,
顧客名
= c.Name,
城市
= c.City };
GridView1.DataBind();
sw.Close();
2.探究查詢
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@font-face
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mso-generic-font-family:roman;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1107304683 0 0 159 0;}
@font-face
{font-family:ˎ̥;
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mso-font-alt:"Times New Roman";
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-format:other;
mso-font-pitch:auto;
mso-font-signature:0 0 0 0 0 0;}
@font-face
{font-family:"/@SimSun";
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mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
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p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-unhide:no;
mso-style-qformat:yes;
mso-style-parent:"";
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margin-bottom:.0001pt;
text-align:justify;
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mso-pagination:none;
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mso-bidi-font-size:12.0pt;
font-family:"Times New Roman","serif";
mso-fareast-font-family:SimSun;
mso-font-kerning:1.0pt;
mso-fareast-language:ZH-CN;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
font-size:10.0pt;
mso-ansi-font-size:10.0pt;
mso-bidi-font-size:10.0pt;
mso-ascii-font-family:"Times New Roman";
mso-fareast-font-family:SimSun;
mso-hansi-font-family:"Times New Roman";
mso-font-kerning:0pt;}
/* Page Definitions */
@page
{mso-page-border-surround-header:no;
mso-page-border-surround-footer:no;}
@page Section1
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mso-footer-margin:36.0pt;
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div.Section1
{page:Section1;}
-->
using System.Data.Common;
using System.Collections.Generic;
NorthwindDataContext ctx = new NorthwindDataContext("server=xxx;database=Northwind;uid=xxx;pwd=xxx");
var select = from c in ctx.Customers where c.CustomerID.StartsWith("A") select new {
顧客
ID = c.CustomerID,
顧客名
= c.Name,
城市
= c.City };
DbCommand cmd = ctx.GetCommand(select);
Response.Write(cmd.CommandText + "<br/>");
foreach (DbParameter parm in cmd.Parameters
)
Response.Write(string.Format("
參數名
:{0},
參數值
:{1}<br/>", parm.ParameterName, parm.Value));
Customer customer = ctx.Customers.First();
<!--
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@font-face
{font-family:SimSun;
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mso-font-alt:宋體;
mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1107304683 0 0 159 0;}
@font-face
{font-family:ˎ̥;
panose-1:0 0 0 0 0 0 0 0 0 0;
mso-font-alt:"Times New Roman";
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-format:other;
mso-font-pitch:auto;
mso-font-signature:0 0 0 0 0 0;}
@font-face
{font-family:"/@SimSun";
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mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-unhide:no;
mso-style-qformat:yes;
mso-style-parent:"";
margin:0cm;
margin-bottom:.0001pt;
text-align:justify;
text-justify:inter-ideograph;
mso-pagination:none;
font-size:10.5pt;
mso-bidi-font-size:12.0pt;
font-family:"Times New Roman","serif";
mso-fareast-font-family:SimSun;
mso-font-kerning:1.0pt;
mso-fareast-language:ZH-CN;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
font-size:10.0pt;
mso-ansi-font-size:10.0pt;
mso-bidi-font-size:10.0pt;
mso-ascii-font-family:"Times New Roman";
mso-fareast-font-family:SimSun;
mso-hansi-font-family:"Times New Roman";
mso-font-kerning:0pt;}
/* Page Definitions */
@page
{mso-page-border-surround-header:no;
mso-page-border-surround-footer:no;}
@page Section1
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margin:72.0pt 90.0pt 72.0pt 90.0pt;
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mso-footer-margin:36.0pt;
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div.Section1
{page:Section1;}
-->
通過
DataContext
的
GetCommand
方法獲取了查詢對應的
DbCommand
，並且輸出了
CommandText
和所有的
DbParameter
3.執行查詢
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4.創建數據庫
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@font-face
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mso-generic-font-family:roman;
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mso-font-signature:-1610611985 1107304683 0 0 159 0;}
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mso-generic-font-family:roman;
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mso-font-pitch:auto;
mso-font-signature:0 0 0 0 0 0;}
@font-face
{font-family:"/@SimSun";
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mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-unhide:no;
mso-style-qformat:yes;
mso-style-parent:"";
margin:0cm;
margin-bottom:.0001pt;
text-align:justify;
text-justify:inter-ideograph;
mso-pagination:none;
font-size:10.5pt;
mso-bidi-font-size:12.0pt;
font-family:"Times New Roman","serif";
mso-fareast-font-family:SimSun;
mso-font-kerning:1.0pt;
mso-fareast-language:ZH-CN;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
font-size:10.0pt;
mso-ansi-font-size:10.0pt;
mso-bidi-font-size:10.0pt;
mso-ascii-font-family:"Times New Roman";
mso-fareast-font-family:SimSun;
mso-hansi-font-family:"Times New Roman";
mso-font-kerning:0pt;}
/* Page Definitions */
@page
{mso-page-border-surround-header:no;
mso-page-border-surround-footer:no;}
@page Section1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;
mso-header-margin:36.0pt;
mso-footer-margin:36.0pt;
mso-paper-source:0;}
div.Section1
{page:Section1;}
-->
testContext ctx = new testContext("server=xxx;database=testdb;uid=xxx;pwd=xxx");
ctx.CreateDatabase();
[
Table(Name = "test")]
public class test
{
[Column(IsPrimaryKey = true, IsDbGenerated = true)]
public int ID { get; set; }
[Column(DbType="varchar(20)")]
public string Name { get; set; }
}
public partial class testContext : DataContext
{
public Table<test> test;
public testContext(string connection) : base(connection) { }
}
5
.使用DbDataReader
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@font-face
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mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1107304683 0 0 159 0;}
@font-face
{font-family:ˎ̥;
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mso-font-alt:"Times New Roman";
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-format:other;
mso-font-pitch:auto;
mso-font-signature:0 0 0 0 0 0;}
@font-face
{font-family:"/@SimSun";
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mso-font-charset:134;
mso-generic-font-family:auto;
mso-font-pitch:variable;
mso-font-signature:3 135135232 16 0 262145 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-unhide:no;
mso-style-qformat:yes;
mso-style-parent:"";
margin:0cm;
margin-bottom:.0001pt;
text-align:justify;
text-justify:inter-ideograph;
mso-pagination:none;
font-size:10.5pt;
mso-bidi-font-size:12.0pt;
font-family:"Times New Roman","serif";
mso-fareast-font-family:SimSun;
mso-font-kerning:1.0pt;
mso-fareast-language:ZH-CN;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
font-size:10.0pt;
mso-ansi-font-size:10.0pt;
mso-bidi-font-size:10.0pt;
mso-ascii-font-family:"Times New Roman";
mso-fareast-font-family:SimSun;
mso-hansi-font-family:"Times New Roman";
mso-font-kerning:0pt;}
/* Page Definitions */
@page
{mso-page-border-surround-header:no;
mso-page-border-surround-footer:no;}
@page Section1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;
mso-header-margin:36.0pt;
mso-footer-margin:36.0pt;
mso-paper-source:0;}
div.Section1
{page:Section1;}
-->
using System.Data.SqlClient;
var conn = new SqlConnection("server=xxx;database=Northwind;uid=xxx;pwd=xxx");
var ctx = new DataContext(conn);
var cmd = new SqlCommand("select * from customers where CustomerID like 'A%'", conn);
conn.Open();
var reader = cmd.ExecuteReader();
GridView1.DataSource = ctx.Translate<Customer>(reader);
GridView1.DataBind();
conn.Close();