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.NET 輕量級 ORM 框架 - Dapper 介紹

Dapper簡單介紹：

Dapper is asingle fileyou can drop in to your project that will extend yourIDbConnectioninterface.

Dapper是一個輕型的開源ORM類，代碼就一個SqlMapper.cs文件，編譯后就40多K的一個很小的Dll. 官方資料：點擊這里

Dapper支持Mysql,SqlLite,Mssql2000,Mssql2005,Oracle等一系列的數據庫，當然如果你知道原理也可以讓它支持Mongo db

Dapper的r支持多表并聯的對象。支持一對多 多對多的關系。并且沒侵入性，想用就用，不想用就不用。無XML無屬性。代碼以前怎么寫現在還怎么寫。

Dapper原理通過Emit反射IDataReader的序列隊列，來快速的得到和產生對象。性能提升了很多；（比采用常規的反射）

Dapper支持net2.0,3.0,3.5,4.0。不過就是要配置下。如果不知道如何配置查看我博客里的在2.0下使用3.5就可以了。

語法十分簡單。并且無須遷就數據庫的設計。

Dapper執行效率：

30W條數據，取其中的一個對象，和第一頁前15條數據，耗時0.0906879秒。這個速度超過Datable。

官方的測試代碼以及數據

Performance ofSELECTmapping over 500 iterations
- POCO serialization

Method	Duration	Remarks
Hand coded (using aSqlDataReader)	47ms
DapperExecuteMapperQuery<Post>	49ms
PetaPoco	52ms	Can be faster
BLToolkit	80ms
SubSonicCodingHorror	107ms
NHibernate SQL	104ms
Linq 2 SQLExecuteQuery	181ms
Entity frameworkExecuteStoreQuery	631ms

Performance ofSELECTmapping over 500 iterations
- dynamic serialization

Method	Duration	Remarks
DapperExecuteMapperQuery (dynamic)	48ms
Massive	52ms
Simple.Data	95ms

Performance ofSELECTmapping over 500 iterations
- typical usage

Method	Duration	Remarks
Linq 2 SQLCompiledQuery	81ms	Not super typical involves complex code
NHibernate HQL	118ms
Linq 2 SQL	559ms
Entity framework	859ms
SubSonicActiveRecord.SingleOrDefault	3619ms

Dapper使用介紹：

如果你使用的是vs2012，可以使用NuGet來進行安裝，會自動添加引用，使用時寫入命名空間即可；

　

　using Dapper;

下面的代碼可以作為使用參考：

publicstaticreadonlystringsqlconnectionString
="Data
Source=xxx;Initial Catalog=Express;User ID=sa;Password=123";

publicstaticreadonlystringmysqlconnectionString =@"server=xxx;database=dddd;uid=xxx;pwd=123;charset='gbk'";

publicstaticSqlConnection SqlConnection()

{

var connection =newSqlConnection(sqlconnectionString);

connection.Open();

returnconnection;

}

publicstaticMySqlConnection MySqlConnection()

{

var connection =newMySqlConnection(mysqlconnectionString);

connection.Open();

returnconnection;

}

調用方法

SqlConnection connection = Program.SqlConnection();

獲得一個實體對象

var d = connection.Query<Dog>("select * from dog where id = 1",null).Single<Dog>();

獲得實體對象結合

var dd = connection.Query<Dog>("select * from dog where id < 10", null).ToList<Dog>();

插入數據

//動態參數
connection.Execute("INSERT INTO dog (Age,Name,Weight) VALUES (@age,@name,@Weight)",
new { @age = i,@name = Guid.NewGuid().ToString(), @Weight = i });   

//直接傳入實體
connection.Execute("INSERT INTO dog (Age,Name,Weight) VALUES (@age,@name,@Weight)",model);

Execute a query and map the results to a strongly typed List



Note: all extension methods assume the connection is already open, they will fail if the connection is closed.



public static IEnumerable<T> Query<T>(this IDbConnection cnn, string sql, object param = null, SqlTransaction transaction = null, bool buffered = true)



Example usage:



publicclassDog

{

    publicint?Age{get;set;}

    publicGuidId{get;set;}

    publicstringName{get;set;}

    publicfloat?Weight{get;set;}



    publicintIgnoredProperty{get{return1;}}

}            

            

var guid =Guid.NewGuid();

var dog = connection.Query<Dog>("select Age = @Age, Id = @Id",new{Age=(int?)null,Id= guid });

            

dog.Count()

    .IsEqualTo(1);



dog.First().Age

    .IsNull();



dog.First().Id

    .IsEqualTo(guid);



Execute a query and map it to a list of dynamic objects



public static IEnumerable<dynamic> Query (this IDbConnection cnn, string sql, object param = null, SqlTransaction transaction = null, bool buffered = true)



This method will execute SQL and return a dynamic list.



Example usage:



 var rows = connection.Query("select 1 A, 2 B union all select 3, 4");



((int)rows[0].A)

   .IsEqualTo(1);



((int)rows[0].B)

   .IsEqualTo(2);



((int)rows[1].A)

   .IsEqualTo(3);



((int)rows[1].B)

    .IsEqualTo(4);



Execute a Command that returns no results



public static int Execute(this IDbConnection cnn, string sql, object param = null, SqlTransaction transaction = null)



Example usage:



connection.Execute(@"

  set nocount on 

  create table #t(i int) 

  set nocount off 

  insert #t 

  select @a a union all select @b 

  set nocount on 

  drop table #t",new{a=1, b=2})

   .IsEqualTo(2);



Execute a Command multiple times



The same signature also allows you to conveniently and efficiently execute a command multiple times (for example to bulk-load data)



Example usage:



connection.Execute(@"insert MyTable(colA, colB) values (@a, @b)",

    new[]{new{ a=1, b=1},new{ a=2, b=2},new{ a=3, b=3}}

  ).IsEqualTo(3);// 3 rows inserted: "1,1", "2,2" and "3,3"



This works for any parameter that implements IEnumerable<T> for some T.

var
dd = connection.Query<Dog>("select
* from dog where id < 10",null).ToList<Dog>();

總結

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