·EntityFramework
·System.ComponentModel.DataAnnotations
·System.Data.Entity
第二步：在App.config文件配置数据库连接字符串
<add name="SQLServer" providerName="System.Data.SqlClient" connectionString="Data Source=localhost;Initial Catalog=Northwind;Pooling=False;user=sa;pwd=sa;" />
第三步：编写程序
①.编写实体类：
using System;
using System.ComponentModel.DataAnnotations;
namespace ConsoleApplication1
{
public class Categories
{
[Key]
public int CategoryID { get; set; }
public string CategoryName { get; set; }
public string Description { get; set; }
public byte[] Picture { get; set; }
}
}②.编写一个DbContext子类：
using System;
using System.Data.Entity;
namespace ConsoleApplication1
{
public class CAContext : DbContext
{
public CAContext()
: base("Name=SQLServer")
{ }
public DbSet<Categories> Categories { get; set; }
//继续添加多个实体类...
}
}③.使用示例：
using System;
using System.Linq;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
CAContext context = new CAContext();
Categories entity;
//添加
entity = new Categories() { CategoryID = 0, CategoryName = "fruit", Description = "-", Picture = null };
context.Categories.Add(entity);
context.SaveChanges();
//修改
entity = context.Categories.Where(c => c.CategoryName == "fruit").First();
if (entity != null)
{
entity.Description = "fruit description.";
context.SaveChanges();
}
//删除
entity = context.Categories.Where(c => c.CategoryName == "fruit").First();
if (entity != null)
{
context.Categories.Remove(entity);
context.SaveChanges();
}
//查询
var categories = context.Categories;
foreach (var item in categories)
Console.WriteLine("{0},{1}", item.CategoryName, item.Description);
Console.ReadKey();
}
}
}
补充说明
[1].实体类主键必须有[Key]约束，否则程序运行会出错：
System.Data.Entity.Edm.EdmEntityType: : EntityType 'Categories' has no key defined. Define the key for this EntityType.
[2].如果实体类名和表名不一致，必须指定表名：
[color=Red][Table("Categories")][/color]
public class Categories2
{
[Key]
public int CategoryID { get; set; }
public string CategoryName { get; set; }
public string Description { get; set; }
public byte[] Picture { get; set; }
}[3].实体类属性只能少于或等于表字段，否则添加记录会出错；
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