//添加单个Donator
public static void CreateSingleDonator()
{
using (var context = new Context())
//Context的实例用了using语句包装起来，这是因为DbContext实现了IDisposable接口。Dbcontext还包含了DbConnection的实例，该实例指向了具有特定连接字符串的数据库。在EF中合适地释放数据库连接和ADO.NET中同等重要
{
context.Database.CreateIfNotExists(); //如果数据库不存在则创建
Donator donators = new Donator() {Name = "单个", Amount = 50, DonateDate = new DateTime(2016, 4, 7)};
context.Donators.Add(donators);
context.SaveChanges();
}
}
//多对多关系
public static void ManyToMany()
{
using (var context = new Context())
{
var person = new Person
{
Name = "比尔盖茨",
};
var person2 = new Person
{
Name = "乔布斯",
};
context.Persons.Add(person);
context.Persons.Add(person2);
var company = new Company
{
CompanyName = "微软",
};
company.Persons.Add(person);
company.Persons.Add(person2);
context.Companies.Add(company);
context.SaveChanges();
}
}
//一对一关系
public static void OneToOne()
{
using (var context = new Context())
{
var student = new Student
{
CollegeName = "XX大学",
EnrollmentDateTime = DateTime.Parse("2016-7-6"),
Person = new Person
{
Name = "学生名",
}
};
context.Students.Add(student);
context.SaveChanges();
}
}
//一对多关系， 主实体有查询属性
public static void OnToManySelect()
{
using (var context = new Context())
{
var donatorType = new DonatorType()
{
Name = "博客园园友",
Donators = new List<Donator>
{
new Donator
{
Amount=6,
Name="一对多关系，主实体有查询属性",
DonateDate=DateTime.Parse("2016-7-6"),
PayWays=new List<PayWay>
{
new PayWay{Name="支付宝" },
new PayWay{ Name="微信"}
}
}
}
};
var donatorType2 = new DonatorType
{
Name = "非博客园园友",
Donators = new List<Donator>
{
new Donator
{
Amount = 10,
Name = "一对多关系",
DonateDate = DateTime.Parse("2016-4-27"),
PayWays = new List<PayWay> {new PayWay {Name = "支付宝"}, new PayWay {Name = "微信"}}
}
}
};
context.DonatorTypes.Add(donatorType);
context.DonatorTypes.Add(donatorType2);
context.SaveChanges();
}
}
//一对多关系， 自定义配置链接
public static void OneToManyCustom()
{
using (var context = new Context())
{
var donator = new Donator
{
Amount = 6,
Name = "一对多时，添加的捐赠者",
DonateDate = DateTime.Parse("2016-7-6")
};
donator.PayWays.Add(new PayWay { Name = "支付宝" });
donator.PayWays.Add(new PayWay { Name = "微信" });
context.Donators.Add(donator);
context.SaveChanges();
}
}
//删除Donators
public static void DeleteDonators()
{
using (var context = new Context())
{
var toBeDeletedDonator = context.Donators.Single(d => d.Name == "多个11已修改");//根据Name找到要删除的目标测试数据
context.SaveChanges();//最后持久化到数据库
}
}
//更新Donator
public static void UpdateDonators()
{
using (var context = new Context())
{
var donators = context.Donators;
if (donators.Any())//any扩展方法来判断序列中是否由元素，
{
var toBeUpdatedDonator = donators.First(d => d.Name =="多个11");//然后使用First扩展方法来找到元素
toBeUpdatedDonator.Name = "多个11已修改";//然后给目标对象的Name属性赋予新值，
context.SaveChanges();//最后调用SaveChanges方法
}
}
}
