C# ORM学习笔记：Dapper基本用法

一、基础知识

1.1、Dapper简介

Dapper是.NET下的一个micro ORM，它和Entity Framework或NHibnate不同，属于轻量级并且是半自动的（实体类都要自己写）。假如你喜欢原生的Sql语句，又喜欢ORM的简单，那你一定会喜欢上Dapper这款ORM。

1.2、Dapper优点

1）轻量。只有一个文件（SqlMapper.cs）。

2）速度快。Dapper的速度接近于IDataReader，取列表的数据超过了DataTable。

3）支持多种数据库。包括SQLite、SqlCe、Firebird、Oracle、MySQL、PostgreSQL、SQL Server。

4）可以映射一对一、一对多、多对多等多种关系。

5）性能高。通过Emit反射IDataReader的序列队列，来快速地得到和产生对象。

1.3、Dapper安装

此处使用Dapper扩展库Dapper.SimpleCRUD，它也会默认安装Dapper（依赖项）：

项目右键->管理 NuGet 程序包->Dapper.SimpleCRUD。

C# ORM学习笔记：Dapper基本用法

二、数据准备

2.1、数据表

在SQL Server中创建4个数据表，分别是：Student（学生表）、Teacher（教师表）、Course（课程表）、Record（成绩表）。

--学生表
CREATE TABLE [dbo].[Student](
    [StudentID] [INT] IDENTITY(1,1) NOT NULL,
    [Name] [NVARCHAR](50) NULL,
    [Age] [SMALLINT] NULL,
    [Gender] [NVARCHAR](10) NULL,
 CONSTRAINT [PK_Student] PRIMARY KEY CLUSTERED 
(
    [StudentID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--教师表
CREATE TABLE [dbo].[Teacher](
    [TeacherID] [INT] IDENTITY(1,1) NOT NULL,
    [Name] [NVARCHAR](50) NULL,
 CONSTRAINT [PK_Teacher] PRIMARY KEY CLUSTERED 
(
    [TeacherID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--课程表
CREATE TABLE [dbo].[Course](
    [CourseID] [int] IDENTITY(1,1) NOT NULL,
    [Name] [nvarchar](50) NULL,
    [TeacherID] [int] NULL,
 CONSTRAINT [PK_Course] PRIMARY KEY CLUSTERED 
(
    [CourseID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--成绩表
CREATE TABLE [dbo].[Record](
    [StudentID] [INT] NOT NULL,
    [CourseID] [INT] NOT NULL,
    [Score] [NUMERIC](8, 2) NULL,
 CONSTRAINT [PK_Score] PRIMARY KEY CLUSTERED 
(
    [StudentID] ASC,
    [CourseID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--学生表数据插入
INSERT INTO Student (Name,Age,Gender)
SELECT N'刘一',18,N'female'
UNION
SELECT N'陈二',19,N'female'
UNION
SELECT N'张三',18,N'male'
UNION
SELECT N'李四',19,N'male'
UNION
SELECT N'王五',18,N'male'
UNION
SELECT N'赵六',19,N'male'
UNION
SELECT N'孙七',19,N'female'

--教师表数据插入
INSERT INTO Teacher (Name)
SELECT N'周八'
UNION
SELECT N'吴九'
UNION
SELECT N'郑十'

--课程表数据插入
INSERT INTO Course (Name,TeacherID)
SELECT N'离散数学',1
UNION
SELECT N'程序设计',2
UNION
SELECT N'数据结构',3

--成绩表数据插入
INSERT INTO Record (StudentID,CourseID,Score )
SELECT 1,1,90
UNION
SELECT 2,1,91
UNION
SELECT 3,1,89
UNION
SELECT 4,1,75
UNION
SELECT 5,1,96
UNION
SELECT 6,1,78
UNION
SELECT 7,1,83
UNION
SELECT 1,2,86
UNION
SELECT 2,2,92
UNION
SELECT 3,2,77
UNION
SELECT 4,2,71
UNION
SELECT 5,2,66
UNION
SELECT 6,2,87
UNION
SELECT 7,2,93
UNION
SELECT 1,3,81
UNION
SELECT 2,3,90
UNION
SELECT 3,3,88
UNION
SELECT 4,3,82
UNION
SELECT 5,3,93
UNION
SELECT 6,3,91
UNION
SELECT 7,3,84

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