.NET 轻量级 ORM 框架

Dapper简单介绍：

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

Dapper是一个轻型的开源ORM类，代码就一个SqlMapper.cs文件，编译后就40多K的一个很小的Dll. 官方资料：点击这里

Dapper支持Mysql,SqlLite,Mssql2000,Mssql2005,Oracle等一系列的数据库，当然如果你知道原理也可以让它支持Mongo db

Dapper的r支持多表并联的对象。支持一对多多对多的关系。并且没侵入性，想用就用，不想用就不用。无XML无属性。代码以前怎么写现在还怎么写。

Dapper原理通过Emit反射IDataReader的序列队列，来快速的得到和产生对象。性能提升了很多；（比采用常规的反射）

Dapper支持net2.0,3.0,3.5,4.0。不过就是要配置下。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。

语法十分简单。并且无须迁就数据库的设计。

Dapper执行效率：

30W条数据，取其中的一个对象，和第一页前15条数据，耗时0.0906879秒。这个速度超过Datable。

官方的测试代码以及数据

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使用介绍：

如果你使用的是vs2012，可以使用NuGet来进行安装，会自动添加引用，使用时写入命名空间即可；

　using Dapper;

下面的代码可以作为使用参考：

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

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

public static SqlConnection SqlConnection()

{

var connection = new SqlConnection(sqlconnectionString);

connection.Open();

return connection;

}

public static MySqlConnection MySqlConnection()

{

var connection = new MySqlConnection(mysqlconnectionString);

connection.Open();

return connection;

}

调用方法

SqlConnection connection = Program.SqlConnection();

获得一个实体对象

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

获得实体对象结合

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

插入数据

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

//直接传入实体
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();

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[].A)

   .IsEqualTo();

((int)rows[].B)

   .IsEqualTo();

((int)rows[].A)

   .IsEqualTo();

((int)rows[].B)

    .IsEqualTo();

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=, b=})

   .IsEqualTo();

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=, b=},new{ a=, b=},new{ a=, b=}}

  ).IsEqualTo();// 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>();