CSharp: Relational mapping in donet using Entity Framework

 sql script

--dbo.Students
--Id int identity
--Name 
--Age byte
--CreatedTime date
-- ModifiedTime date
IF EXISTS (select * from sysobjects where id = object_id(N'[dbo].Students') and OBJECTPROPERTY(id, N'IsUserTable') = 1) 
DROP TABLE Students 
GO
create table Students
(
	Id INT IDENTITY(1,1) PRIMARY KEY,
	[Name] nvarchar(50) not null,
	Age tinyint  null,
	CreatedTime date null,
	ModifiedTime date null
)
go

insert into Students([Name],Age,CreatedTime,ModifiedTime) values('sibodu',12,getdate(),getdate())
go

select * from Students
go

--StudentContact  ContactNumber

IF EXISTS (select * from sysobjects where id = object_id(N'[dbo].StudentContact') and OBJECTPROPERTY(id, N'IsUserTable') = 1) 
DROP TABLE StudentContact 
GO
create table StudentContact
(
	Id INT IDENTITY(1,1) PRIMARY KEY,
	StudentId int
	   FOREIGN KEY REFERENCES Students(Id),
	ContactNumber nvarchar(50) null
)
go





-- dbo.Courses
--Id  int identity
--Name
--MaximumStrength int
--CreatedTime
--ModifiedTime
--
IF EXISTS (select * from sysobjects where id = object_id(N'[dbo].Courses') and OBJECTPROPERTY(id, N'IsUserTable') = 1) 
DROP TABLE Courses 
GO
create table Courses
(
	Id INT IDENTITY(1,1) PRIMARY KEY,
	[Name] nvarchar(50) not null,
	MaximumStrength int null,
	CreatedTime date null,
	ModifiedTime date null
)
go

insert into Courses([Name],MaximumStrength,CreatedTime,ModifiedTime) values('語文',25,getdate(),getdate())
go


select * from Courses
go



-- DropForeignKey("dbo.Orders", "CustomerId", "dbo.Customers");
-- DropForeignKey("dbo.Products", "CategoryId", "dbo.Categories");

--SutdentCourcese

IF EXISTS (select * from sysobjects where id = object_id(N'[dbo].SutdentCourcese') and OBJECTPROPERTY(id, N'IsUserTable') = 1) 
DROP TABLE SutdentCourcese 
GO
create table SutdentCourcese
(
	Id INT IDENTITY(1,1) PRIMARY KEY,
	StudentId int
		FOREIGN KEY REFERENCES Students(Id),
	CourseId int
	    FOREIGN KEY REFERENCES Courses(Id)
)
go

select * from SutdentCourcese
go

　　

using EntityFramework6.Enity;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity.Core.Metadata;
using System;
using System.ComponentModel.DataAnnotations.Schema;
//using Microsoft.EntityFrameworkCore.Metadata;

namespace EntityFramework6.Entity
{

    /// <summary>
    /// 學生
    /// </summary>
    [Table("Student")]
    public class Student : BaseEntity
    {

        [Display(Name = "姓名")]
        public string Name { get; set; }

        [Display(Name = "年齡")]
        public byte Age { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public DateTime CreatedTime { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public DateTime ModifiedTime { get; set; }


        /// <summary>
        /// 
        /// </summary>
        [Display(Name = "聯繫方式")]
        public virtual StudentContact Contact { get; set; }


        /// <summary>
        /// 課程表
        /// </summary>
        [Display(Name = "課程表")]
        public virtual ICollection<SutdentCourcese> SutdentCourcese { get; set; }
    }
}


using EntityFramework6.Enity;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity.Core.Metadata;
using System.ComponentModel.DataAnnotations.Schema;

namespace EntityFramework6.Entity
{


    /// <summary>
    /// 課程
    /// </summary>
    [Table("Courses")]
    public class Course : BaseEntity
    {

        /// <summary>
        /// 課程名稱
        /// </summary>
        [Display(Name = "課程名稱")]
        public string Name { get; set; }
        /// <summary>
        /// 課時時長
        /// </summary>

        [Display(Name = "課時時長")]
        public int MaximumStrength { get; set; }


        /// <summary>
        /// 課程
        /// </summary>
        [Display(Name = "課程表")]
        public virtual ICollection<SutdentCourcese> SutdentCourcese { get; set; }
    }
}


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using EntityFramework6.Enity;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity.Core.Metadata;
using System.ComponentModel.DataAnnotations.Schema;


namespace EntityFramework6.Entity
{
    /// <summary>
    /// 學生課程表
    /// </summary>
    [Table("SutdentCourcese")]
    public class SutdentCourcese
    {

        /// <summary>
        /// 
        /// </summary>
        [Display(Name = "ID")]
        public int Id { get; set; }
        /// <summary>
        /// 學生ID
        /// </summary>
        [Display(Name = "學生ID")]
        [ForeignKey("Student")]
        public int StudentId { get; set; }

        /// <summary>
        /// 學生ID
        /// </summary>
        [Display(Name = "課程ID")]
        [ForeignKey("Course")]
        public int CourseId { get; set; }

        /// <summary>
        /// 學生
        /// </summary>
        [Display(Name = "學生")]
        public virtual Student Student { get; set; }

        /// <summary>
        /// 課程
        /// </summary>
        [Display(Name = "課程")]
        public virtual Course Course { get; set; }
    }
}


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using EntityFramework6.Enity;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity.Core.Metadata;
using System.ComponentModel.DataAnnotations.Schema;

//using Microsoft.EntityFrameworkCore.Metadata;

namespace EntityFramework6.Entity
{

    /// <summary>
    /// 學生聯繫表
    /// </summary>
    [Table("StudentContact")]
    public class StudentContact
    {

        /// <summary>
        /// 
        /// </summary>
        [Display(Name = "ID")]
        public int Id { get; set; }
        /// <summary>
        /// 聯繫電話
        /// </summary>

        [Display(Name = "聯繫電話")]
  
        public string ContactNumber { get; set; }

        /// <summary>
        /// 學生ID
        /// </summary>
        [Display(Name = "學生ID")]
        [ForeignKey("Student")]
        public int StudentId { get; set; }

        /// <summary>
        /// 學生
        /// </summary>
        [Display(Name = "學生")]
        public virtual Student Student {get;set;}


    }
}

　　

Mapping

 

using EntityFramework6.Entity;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.ModelConfiguration;

//https://entityframework.net/one-to-one-relationship
//https://www.entityframeworktutorial.net/code-first/foreignkey-dataannotations-attribute-in-code-first.aspx
//https://github.com/dotnet/ef6
//https://docs.microsoft.com/en-us/ef/ef6/


namespace EntityFramework6.Map
{

    /// <summary>
    /// 
    /// </summary>
    public class StudentMap : EntityTypeConfiguration<Student>
    {
        /// <summary>
        /// 
        /// </summary>
        public StudentMap()
        {
            //table  
            ToTable("Students");

            //key
            HasKey(t => t.Id);

            //fields
            Property(x => x.Id)
                .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
            Property(x => x.Name).HasColumnType("VARCHAR").HasMaxLength(50);
            Property(x => x.Age);
            Property(x => x.CreatedTime);
            Property(x => x.ModifiedTime);

            //relationship Many-to-Many Relationishhip 多對多 課程表
            //HasMany(t => t.SutdentCourcese).WithMany(c => c.Student)
            //    .Map(t => t.ToTable("SutdentCourcese")
            //    .MapLeftKey("StudentId")
            //    .MapRightKey("CourseId"));

            //多對一
            HasMany(t => t.SutdentCourcese)
                .WithRequired(w => w.Student)
                .HasForeignKey(o => o.StudentId);




            //realationship One-to-One 一對一 聯繫表
            HasOptional(x => x.Contact)
                .WithOptionalDependent(l => l.Student);

           // HasRequired(x => x.Contact).WithOptional(l => l.Student);



        }
    }
}


using EntityFramework6.Entity;
using System.Data.Entity.ModelConfiguration;
using System.ComponentModel.DataAnnotations.Schema;



namespace EntityFramework6.Map
{

    /// <summary>
    /// geovindu
    /// </summary>
    public class CourseMap : EntityTypeConfiguration<Course>
    {
        public CourseMap()
        {
            //table
            ToTable("Courses");

            //key
            HasKey(k => k.Id);

            //property
            Property(t => t.Id).HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity);
            Property(t => t.Name).HasColumnType("VARCHAR").HasMaxLength(50);
            Property(t => t.MaximumStrength);
            Property(t => t.CreatedTime);
            Property(t => t.ModifiedTime);


            //HasMany(t => t.SutdentCourcese).WithMany(c => c.Course)
            //    .Map(t => t.ToTable("SutdentCourcese")
            //    .MapLeftKey("CourseId")
            //    .MapRightKey("StudentId"));
            //
            //HasMany(c => c.SutdentCourcese).WithMany(l => l.Course)
            //    .Map(t => t.ToTable("SutdentCourcese")
            //    .MapLeftKey("CourseId"));

            //多對多
            //HasMany(c => c.Students).WithMany(l => l.Courses);
            //HasMany(c => c.SutdentCourcese).WithMany(l => l.Course);

            //多對一
            HasMany(c => c.SutdentCourcese).WithRequired(l => l.Course)
                .HasForeignKey(k=>k.CourseId);



           // HasMany(c => c.Students).WithRequired(l => l.);

        }
    }
}


using EntityFramework6.Entity;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.ModelConfiguration;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace EntityFramework6.Map
{

    /// <summary>
    /// 
    /// </summary>
    public  class SutdentCourceseMap : EntityTypeConfiguration<SutdentCourcese>
    {


        /// <summary>
        /// 
        /// </summary>
        public SutdentCourceseMap()
        {
            //table
            ToTable("SutdentCourcese");

            //key
            HasKey(t => t.Id);

            //fields
            Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

            Property(x => x.StudentId)
                .HasColumnName("StudentId")
                .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

            Property(x => x.CourseId)
              .HasColumnName("CourseId")
              .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

            //relationship one-to-one 一對多
            HasRequired(c => c.Course).WithMany(l => l.SutdentCourcese); //Contact SutdentCourcese

            HasRequired(s => s.Student).WithMany(l => l.SutdentCourcese);

            //HasMany  多對多
            //HasMany(c => c.Course).WithMany(l => l.SutdentCourcese);
            //HasMany(s => s.Student).WithMany(l => l.SutdentCourcese);


        }
    }
}


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.ModelConfiguration;
using EntityFramework6.Entity;
//https://www.entityframeworktutorial.net/code-first/foreignkey-dataannotations-attribute-in-code-first.aspx


namespace EntityFramework6.Map
{

    /// <summary>
    /// 
    /// </summary>
    public class StudentContactMap:EntityTypeConfiguration<StudentContact>
    {


        public StudentContactMap()
        {
            //table
            ToTable("StudentContact");

            //key
            HasKey(t => t.Id);

            //fields
            Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
            Property(x=>x.StudentId)
                .HasColumnName("StudentId")
                .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
            Property(x => x.ContactNumber);

            //relationship one-to-one 一對一
            //HasRequired(s => s.Student).WithOptional(l => l.Contact); //Student in class  Contact


            HasOptional(s=>s.Student).WithOptionalPrincipal(l=>l.Contact);
        }

    }
}

　　

調用：

                //查詢集合
                var customers = ctx.Customers;

                //var names = customers
                //    .Select(x => x.Name)
                //    //.Take(10)
                //    .OrderBy(d=>1)
                //    .Skip(5)                    
                //    .ToList();

                var names = customers
                    .Select(x => x.Name)
                    .Take(10)
                    .OrderBy(d => 1)
                    //.Skip(5)
                    .ToList();

                foreach (var name in names)
                {
                    Console.WriteLine(name + "\n\t");
                }

                //原始查詢
                var cus = ctx.Database.SqlQuery<Customer>("SELECT * FROM dbo.Customers").ToList();

                foreach (var cs in cus)
                {
                    Console.WriteLine("name:"+cs.Name + "\n\t");
                }

                var id = 1;
                var par = new SqlParameter[]
                    { 
                        new SqlParameter(){ ParameterName="@id",SqlDbType=SqlDbType.Int,Value=id },
                    };
                var cust = ctx.Database.SqlQuery<Customer>("SELECT * FROM dbo.Customers where id=@id", par).ToList();
                foreach (var ducs in cust)
                {
                    Console.WriteLine("姓名:" + ducs.Name + "\n\t");
                }

　　

輸出：

SELECT
    [Project1].[Name] AS [Name]
    FROM ( SELECT TOP (10)
        1 AS [C1],
        [c].[Name] AS [Name]
        FROM [dbo].[Customers] AS [c]
    )  AS [Project1]
    ORDER BY [Project1].[C1] ASC


-- Executing at 2023/1/29 11:48:02 +08:00

-- Completed in 178 ms with result: SqlDataReader



塗年生

塗聚文

test

geovindu

江城

保中

王二

李三

張四

趙五

SELECT * FROM dbo.Customers


-- Executing at 2023/1/29 11:48:03 +08:00

-- Completed in 10 ms with result: SqlDataReader



name:塗年生

name:塗聚文

name:test

name:geovindu

name:江城

name:保中

name:王二

name:李三

name:張四

name:趙五

name:陳六

name:劉七

name:徐八

name:何九

SELECT * FROM dbo.Customers where id=@id


-- @id: '1' (Type = Int32, IsNullable = false)

-- Executing at 2023/1/29 11:48:03 +08:00

-- Completed in 7 ms with result: SqlDataReader



姓名:塗年生