EF基础篇-Code First

Code First 通过代码反向生成数据库，无需关心数据库方面

1 新建一个控制台项目

2 打开NuGet程序包管理，添加EntityFramework

添加完成后查看是否有如下两个引用

3 代码编写及配置

新建Goods类

 class Goods
    {
        [Key]
        public int GID { get; set; }
        public string GName { get; set; }
        public int GPrice { get; set; }
        public int Shelf_SID { get; set; }
    }

新建Shelves

class Shelves
    {
        [Key]
        public int SID { get; set; }
        public string SPosition { get; set; }
        public string SName { get; set; }
    }

新建上下文SaleContext

 class SaleContext: DbContext
    {
        public SaleContext(): base("name=SaleMarket")
        {
        }

        public virtual DbSet<Goods> Goods { get; set; }
        public virtual DbSet<Shelves> Shelf { get; set; }
    }

App.config中添加数据库连接

<connectionStrings>
        <add name="SaleMarket" connectionString="data source=IP;initial catalog=SaleMarket;User Id=sa;Password=******" providerName="System.Data.SqlClient"/>
    </connectionStrings>

4 数据库创建及实例操作

           using (var smContext=new SaleContext())
            {
                if (smContext.Database.CreateIfNotExists())
                {
                    Console.WriteLine("创建成功");
                }
                else
                {
                    Console.WriteLine("数据库已存在");
                }
                //CRUD
                List<Shelves> s1 = new List<Shelves>
                {
                    new Shelves
                    {
                        SID=1,
                        SName="糖果区",
                        SPosition="1L-09N",
                        
                    },
                    new Shelves
                    {
                        SID=2,
                        SName="瓜子区",
                        SPosition="1L-08N",
                        
                    }
                };
                List<Goods> g1 = new List<Goods>
                {
                    new Goods
                    {
                        GID=1,
                        GName="大白兔",
                        GPrice=16,
                        Shelf_SID=1
                    },
                    new Goods
                    {
                         GID=2,
                         GName="巧克力",
                         GPrice=32,
                         Shelf_SID=1
                    },
                    new Goods
                    {
                        GID=3,
                        GName="焦糖味",
                        GPrice=15,
                        Shelf_SID=2
                    },
                    new Goods
                    {
                        GID=4,
                        GName="原味",
                        GPrice=12,
                        Shelf_SID=2
                    },
                    new Goods
                    {
                        GID=5,
                        GName="五香味",
                        GPrice=10,
                        Shelf_SID=2
                    }  
                };
                smContext.Shelf.AddRange(s1);
                smContext.Goods.AddRange(g1);
                smContext.SaveChanges();
                var p = smContext.Goods.Join(smContext.Shelf, g => g.Shelf_SID, s => s.SID, (g, s) => new { g.GName,g.GPrice,s.SName,s.SPosition }).Where(gs=>gs.GPrice>16);
                foreach (var item in p)
                {
                    Console.WriteLine($"{ item.GName}在{item.SPosition}的{item.SName}，价格是{item.GPrice}");
                }
            }
            Console.ReadKey();        

打开数据库查看，数据库已创建

结果显示