//删
protected void Button3_Click(object sender, EventArgs e)
{
EFModelEntities efmodelentities = new EFModelEntities();
EFStudet efstudet = new EFStudet()
{
Id = 6
};
//确定需要处理的类
efmodelentities.Entry <EFStudet>(efstudet).State = System.Data.Entity.EntityState.Deleted;
efmodelentities.SaveChanges();
//第二种方法
//var studentlist = from u in efmodelentities.EFStudet
// where u.Id == 5
// select u;
//EFStudet efstudet = studentlist.FirstOrDefault();//返回第一条数据,没有值返回null
//if (efstudet != null)
//{
// efmodelentities.EFStudet.Remove(efstudet);
// int result = efmodelentities.SaveChanges();//受影响的行数
//}
//else {
// Response.Write("不存在");
//}
}
//增
protected void Button1_Click(object sender, EventArgs e)
{
EFStudet efstudet = new EFStudet();
efstudet.Name = "许柯";
efstudet.Age = 25;
efstudet.Six = "男";
EFModelEntities efmodelentities = new EFModelEntities();
efmodelentities.EFStudet.Add(efstudet);
int result = efmodelentities.SaveChanges();//受影响的行数
Response.Write(efstudet.Id);
}
//查
protected void Button2_Click(object sender, EventArgs e)
{
EFModelEntities efmodelentities = new EFModelEntities();
//linq表达式
//泛型集合
var studentlist = from u in efmodelentities.EFStudet
where u.Id == 5
select u;
//运行到in时生成sql语句,延迟加载机制,数据用时才查询
foreach (EFStudet student in studentlist)
{
Response.Write(student.Name);
}
}
//改
protected void Button4_Click(object sender, EventArgs e)
{
EFModelEntities efmodelentities = new EFModelEntities();
var studentlist = from u in efmodelentities.EFStudet
where u.Id > 3
select u;
//新建类需要带着主键才能更新
EFStudet efstudet = new EFStudet();
efstudet.Id = 2;
efstudet.Name = "任晓东";
efmodelentities.Entry <EFStudet>(efstudet).State = System.Data.Entity.EntityState.Modified;
//foreach (EFStudet ss in studentlist) {
// ss.Name = "王梦梦";
// efmodelentities.Entry<EFStudet>(ss).State = System.Data.Entity.EntityState.Modified;
//}
//efstudet.Name = "王梦梦";
//efmodelentities.Entry<EFStudet>(efstudet).State = System.Data.Entity.EntityState.Modified;
efmodelentities.SaveChanges();
}