1 创建各个实体类

2 创建一个空数据模型，然后删除掉，为了引入Entity Framework和System.Data.Entity

3 为实体类增加标注

4 为实体增加导航属性

5 在App.config configuration标签里面增加connectionStrings标签，并增加连接字符串

6 创建数据操作类继承DbContext ，构造函数参数为“name=connStr”

7 增加两个DbSet属性，对应操作的实体

8 重写OnModelCreating方法，使得生成的表不包含复数；

9 调用context.Database.CreateIfNotExists()在对应的数据库下面生成表

10 通过数据操作类操作表

//ClassInfo

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstDemo
{
    public class ClassInfo
    {
        [Key]
        public int Id { get; set; }
        [Required]
        [StringLength(32)]
        public string ClassName { get; set; }
        [Required]
        public DateTime CreateTime { get; set; }
        public ICollection<StudentInfo> StudentInfo { get; set; }
    }

}

//StudentInfo

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstDemo
{
    public class StudentInfo
    {
        [Key]
        public int Id { get; set; }
        [Required]
        [StringLength(32)]
        public string StudentName { get; set; }
        [Required]
        public DateTime CreateTime { get; set; }
        [Required]
        public ClassInfo ClassInfo { get; set; }
    }

}

//MyDataContext

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstDemo
{
    public class MyDataContext:DbContext
    {
        public MyDataContext()
            : base("name = ConnStr")
        {
        }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
        }

public DbSet<ClassInfo> ClassInfo { get; set; }
        public DbSet<StudentInfo> StudentInfo { get; set; }

}

}

//主方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CodeFirstDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            MyDataContext db = new MyDataContext();
            db.Database.CreateIfNotExists();
            ClassInfo classInfo = new ClassInfo();
            classInfo.ClassName = "abc";
            classInfo.CreateTime = DateTime.Now;
            db.ClassInfo.Add(classInfo);

StudentInfo stu1 = new StudentInfo();
            stu1.StudentName = "zhangsan";
            stu1.CreateTime = DateTime.Now;
            stu1.ClassInfo = classInfo;
            StudentInfo stu2 = new StudentInfo();
            stu2.StudentName = "Lisi";
            stu2.CreateTime = DateTime.Now;
            stu2.ClassInfo = classInfo;
            db.StudentInfo.Add(stu1);
            db.StudentInfo.Add(stu2);
            db.SaveChanges();
        }
    }
}