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

1  class Goods
2     {
3         [Key]
4         public int GID { get; set; }
5         public string GName { get; set; }
6         public int GPrice { get; set; }
7         public int Shelf_SID { get; set; }
8     }
View Code

新建Shelves

1 class Shelves
2     {
3         [Key]
4         public int SID { get; set; }
5         public string SPosition { get; set; }
6         public string SName { get; set; }
7     }
View Code

新建上下文SaleContext

1  class SaleContext: DbContext
2     {
3         public SaleContext(): base("name=SaleMarket")
4         {
5         }
6 
7         public virtual DbSet<Goods> Goods { get; set; }
8         public virtual DbSet<Shelves> Shelf { get; set; }
9     }
View Code

App.config中添加数据库连接

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

4 数据库创建及实例操作

 1            using (var smContext=new SaleContext())
 2             {
 3                 if (smContext.Database.CreateIfNotExists())
 4                 {
 5                     Console.WriteLine("创建成功");
 6                 }
 7                 else
 8                 {
 9                     Console.WriteLine("数据库已存在");
10                 }
11                 //CRUD
12                 List<Shelves> s1 = new List<Shelves>
13                 {
14                     new Shelves
15                     {
16                         SID=1,
17                         SName="糖果区",
18                         SPosition="1L-09N",
19                         
20                     },
21                     new Shelves
22                     {
23                         SID=2,
24                         SName="瓜子区",
25                         SPosition="1L-08N",
26                         
27                     }
28                 };
29                 List<Goods> g1 = new List<Goods>
30                 {
31                     new Goods
32                     {
33                         GID=1,
34                         GName="大白兔",
35                         GPrice=16,
36                         Shelf_SID=1
37                     },
38                     new Goods
39                     {
40                          GID=2,
41                          GName="巧克力",
42                          GPrice=32,
43                          Shelf_SID=1
44                     },
45                     new Goods
46                     {
47                         GID=3,
48                         GName="焦糖味",
49                         GPrice=15,
50                         Shelf_SID=2
51                     },
52                     new Goods
53                     {
54                         GID=4,
55                         GName="原味",
56                         GPrice=12,
57                         Shelf_SID=2
58                     },
59                     new Goods
60                     {
61                         GID=5,
62                         GName="五香味",
63                         GPrice=10,
64                         Shelf_SID=2
65                     }  
66                 };
67                 smContext.Shelf.AddRange(s1);
68                 smContext.Goods.AddRange(g1);
69                 smContext.SaveChanges();
70                 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);
71                 foreach (var item in p)
72                 {
73                     Console.WriteLine($"{ item.GName}在{item.SPosition}的{item.SName}，价格是{item.GPrice}");
74                 }
75             }
76             Console.ReadKey();
View Code

打开数据库查看，数据库已创建

结果显示

posted @ 2021-02-24 16:09  htiu  阅读(66)  评论(0)  编辑  收藏  举报