转自:https://blog.csdn.net/hanjun0612/article/details/52170204

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

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("select * from dog where id = 1",null).Single();

获得实体对象结合

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

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 Query(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("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 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 for some T.

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