Dapper 介绍
转载：http://www.csdn123.com/html/itweb/20130918/125194_125199_125210.htm
.NET 轻量级 ORM 框架 - Dapper 介绍
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(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>();
