?轉載：http://***/html/itweb/20130918/125194_125199_125210.htm

.NET 輕量級 ORM 框架 - Dapper 介紹

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Dapper簡單介紹：

Dapper is a?single file?you can drop in to your project that will extend your?IDbConnection?interface.

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：

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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 of?SELECT?mapping over 500 iterations - POCO serialization

Method	Duration	Remarks
Hand coded (using a?SqlDataReader)	47ms
Dapper?ExecuteMapperQuery<Post>	49ms
PetaPoco	52ms	Can be faster
BLToolkit	80ms
SubSonic?CodingHorror	107ms
NHibernate SQL	104ms
Linq 2 SQL?ExecuteQuery	181ms
Entity framework?ExecuteStoreQuery	631ms

Performance of?SELECT?mapping over 500 iterations - dynamic serialization

Method	Duration	Remarks
Dapper?ExecuteMapperQuery (dynamic)	48ms
Massive	52ms
Simple.Data	95ms

Performance of?SELECT?mapping over 500 iterations - typical usage

Method	Duration	Remarks
Linq 2 SQL?CompiledQuery	81ms	Not super typical involves complex code
NHibernate HQL	118ms
Linq 2 SQL	559ms
Entity framework	859ms
SubSonic?ActiveRecord.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;

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下面的代碼可以作為使用參考：

public?static?readonly?string?sqlconnectionString =?"Data Source=xxx;Initial Catalog=Express;User ID=sa;Password=123";

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public?static?readonly?string?mysqlconnectionString =?@"server=xxx;database=dddd;uid=xxx;pwd=123;charset='gbk'";

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public?static?SqlConnection SqlConnection()

{

????var connection =?new?SqlConnection(sqlconnectionString);

????connection.Open();

????return?connection;

}

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public?static??MySqlConnection? MySqlConnection()

{

????var connection =?new?MySqlConnection(mysqlconnectionString);

????connection.Open();

????return?connection;

}

調用方法

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SqlConnection connection = Program.SqlConnection();

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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);

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Execute a query and map the results to a strongly typed ListNote: 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 objectspublic 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 resultspublic 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 timesThe 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.

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

轉載于:https://www.cnblogs.com/hanjun0612/p/9779879.html

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