EF使用CodeFirst方式生成数据库&技巧经验

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.Entity.ModelConfiguration.Conventions;
namespace EFDemo.Core.EF
{
/// <summary>
/// EF访问数据库的接口
/// </summary>
public class MyDbContext : System.Data.Entity.DbContext
{
public MyDbContext()
: base("EFDemo")
{
//解决团队开发中，多人迁移数据库造成的修改覆盖问题。
Database.SetInitializer<MyDbContext>(null);
//base.Configuration.AutoDetectChangesEnabled = false;
////关闭EF6.x 默认自动生成null判断语句
//base.Configuration.UseDatabaseNullSemantics = true;
}
public MyDbContext(System.Data.Common.DbConnection oConnection)
: base(oConnection, true)
{
this.Configuration.LazyLoadingEnabled = true;
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
//表名不用复数形式
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
//移除一对多的级联删除约定，想要级联删除可以在 EntityTypeConfiguration<TEntity>的实现类中进行控制
modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
//多对多启用级联删除约定，不想级联删除可以在删除前判断关联的数据进行拦截
modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>(); base.OnModelCreating(modelBuilder);
}
//将实体对象写在这里，就可以生成对应的数据。 如下：
//public DbSet<Demo> Demo { get; set; } }}

namespace EFDemo.Core.Migrations
{
using System;
using System.Data.Entity;
using System.Data.Entity.Migrations;
using System.Linq; internal sealed class Configuration : DbMigrationsConfiguration<EFDemo.Core.EF.MyDbContext>
{
public Configuration()
{
//允许自动迁移
//不然会报错Unable to update database to match the current model because there are pending changes and automatic migration is disabled. Either write the pending model changes to a code-based migration or enable automatic migration. Set DbMigrationsConfiguration.AutomaticMigrationsEnabled to true to enable automatic migration.You can use the Add-Migration command to write the pending model changes to a code-based migration. //允许自动迁移
AutomaticMigrationsEnabled = true;
//自动迁移默认情况下不扔掉列在我们的数据库中的表。如果我们不希望这样的行为，我们可以告诉迁移明确允许数据丢失的配置类的AutomaticMigrationDataLossAllowed属性设置为true。
AutomaticMigrationDataLossAllowed = true;
} protected override void Seed(EF.MyDbContext context)
{ // This method will be called after migrating to the latest version. // You can use the DbSet<T>.AddOrUpdate() helper extension method
// to avoid creating duplicate seed data. E.g.
//
// context.People.AddOrUpdate(
// p => p.FullName,
// new Person { FullName = "Andrew Peters" },
// new Person { FullName = "Brice Lambson" },
// new Person { FullName = "Rowan Miller" }
// );
//
}
}
}

//将实体对象写在这里，就可以生成对应的数据。 如下：
//public DbSet<Demo> Demo { get; set; } public DbSet<Public_Area> Public_Area { get; set; }
public DbSet<T_Classes> T_Classes { get; set; }
public DbSet<T_Student> T_Student { get; set; }

<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<connectionStrings>
<!--生成数据库的连接字符串-->
<add name="EFDemo" connectionString="Data Source=.;Initial Catalog=EFDemoDB;User ID=sa;Password=123456;MultipleActiveResultSets=True;Application Name=EntityFramework" providerName="System.Data.SqlClient" />
</connectionStrings>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="mssqllocaldb" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>
</entityFramework>
</configuration>

<connectionStrings>
<!--操作数据库的连接字符串-->
<add name="EFDemo" connectionString="Data Source=.;Initial Catalog=EFDemoDB;User ID=sa;Password=123456;MultipleActiveResultSets=True;Application Name=EntityFramework" providerName="System.Data.SqlClient" />
</connectionStrings>

public ActionResult Index()
{
using (var db = new Core.EF.MyDbContext())
{
Public_Area area1 = new Public_Area()
{
ID = Guid.NewGuid(),
Name = "河南",
ParentID = Guid.NewGuid() };
db.Public_Area.Add(area1);
Public_Area area2 = new Public_Area()
{
ID = Guid.NewGuid(),
Name = "郑州",
ParentID = area1.ID };
db.Public_Area.Add(area2);
Public_Area area3 = new Public_Area()
{
ID = Guid.NewGuid(),
Name = "新郑",
ParentID = area2.ID };
db.Public_Area.Add(area3); //添加测试数据
T_Classes classes = new T_Classes()
{
Name = "高中三班",
Money =
};
db.T_Classes.Add(classes);
T_Student student = new T_Student()
{
ClassesID = classes.ID,
Name = "张三",
Phone = "",
Sex = true,
ProvinceID = area1.ID,
CityID = area2.ID,
CountyID = area3.ID,
};
db.T_Student.Add(student);
db.SaveChanges();
}
return View();
}