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

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：

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

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;

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";

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;

}

調用方法

SqlConnection connection = Program.SqlConnection();

獲得一個實體對象

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

獲得實體對象結合

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

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 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();

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