摘要：
Dapper原理通过Emit反映了IDataReader的序列队列，以快速获取和生成对象。性能提高了很多；Dapper支持net2.0,3.0,3.5,4.0。Dapper执行效率：30W数据，其中一个是对象，第一页的前15个数据。这需要0.0906879秒。SELECTmappingover 500迭代的官方测试代码和数据性能-POCOserializationMethodDurationRemarksHandcoded47msDapperExecuteMapperQuery＜Post＞49msPetaPoco52msCanbefasterBLToolkit80msSubSonicCodeHorror107msNHibernateSQL104msLinq2SQLExecuteQuery181msEntityframeworkExecuteStoreQuery631msSELECTmapping over 500迭代动态串行化方法DurationRemissionApper的性能Execu teMapperQuery48msMassive52msSimple。数据95ms选择映射500次迭代的性能-典型计算方法持续时间RemarksLinq2SQLCompiledQuery81ms非超典型查询复杂代码NHibernateHQL118ms Linq2SQL 559ms实体框架工作859msSubSonicActiveRecord。SingleOrDefault3619msDapper简介；使用Dapper；以下代码可用作参考：publicstatic readonlystringsqlconnectionString=“DataSource=xxx；InitialCatalog=Express；UserID=sa；Password=123”；publicstaticcreatedonlystringmysqlconnectionString=@“server=xxx；database=dddd；uid=xxx；pwd=123；charset='gbk'”；publicstaticSqlConnectionSqlConnection（）｛varconnection=newSqlConnection；connection.Open（）；returnconnection；｝publicstaticMySqlConnectionMySqlConnection（）｛varconnection=newMySqlConnection；connection.Open（）；returnconnection；｝调用方法SqlConnectionconnection=Program。SqlConnection（）；获取实体对象vard=连接。查询＜狗＞。单身（）；获取实体对象组合vardd=connection。查询＜狗＞。ToList＜Dog＞（）；插入数据//动态参数连接。Execute//直接传入实体连接Execute；执行查询并将结果映射到不同类型的列表注意：所有用于连接的扩展方法都已打开，如果连接关闭，它们将失败。publicstaticEnumerable＜T＞Query＜T＞示例用法：publicclassDog｛publicint？
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<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>();