static void DeleteStudents()
{
//根据主键构建一个对象
Students student = new Students
{
StudentId = 100000
};
//第一种写法：通过设置状态
using (StudentManageDBEntities db = new StudentManageDBEntities())
{
db.Set <Students>().Attach(student);
db.Entry(student).State = EntityState.Deleted;
db.SaveChanges();
}
//第二种写法：通过remove方法
using (StudentManageDBEntities db = new StudentManageDBEntities())
{
db.Set <Students>().Attach(student);
db.Students.Remove(student);
db.SaveChanges();//跟新到数据库（自动生成SQL语句）
}
//第三种写法：先查寻，再删除
using (StudentManageDBEntities db = new StudentManageDBEntities())
{
var stu = db.Students.Where(o => o.StudentId == 100000).FirstOrDefault();
db.Students.Remove(stu);
db.SaveChanges();//跟新到数据库（自动生成SQL语句）
}
}
static void Delete2()
{
StudentManageDBEntities db = new StudentManageDBEntities();
Students student = new Students
{
StudentId = 100013,
};
db.Set <Students>().Attach(student);
db.Entry(student).State = EntityState.Deleted;
//提交
int result = db.SaveChanges();//跟新到数据库（自动生成SQL语句）
Console.WriteLine("影响行数：" + result);
}