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.NET / C# EF中的基础操作（CRUD）

查

public List<users> Querys()
        {
            datatestEntities db = new datatestEntities();
            var a = db.users.ToList();
            return a;
        }
        public users Querys(int id)
        {
            datatestEntities db = new datatestEntities();
            var a = db.users.Find(id);//FirstOrDefault()返回序列中第一个元素
            return a;
        }
知识兔

改

public void Edits(EF.users m)
        {
            datatestEntities db = new datatestEntities();
            db.Entry<users>(m).State = System.Data.Entity.EntityState.Modified;
            db.SaveChanges();
        }
知识兔

增

public void Inserts(users m)
        {
            datatestEntities db = new datatestEntities();
           // var a = db.users.Add(m);
            db.Entry<users>(m).State = System.Data.Entity.EntityState.Added;
            db.SaveChanges();
        }
知识兔

删

public void Deletes(users m)
        {
            datatestEntities db = new datatestEntities();
            //方法1
            //db1.Entry<users>(m).State = System.Data.Entity.EntityState.Unchanged;//var a = db1.users.Remove(m);//System.InvalidOperationException:“无法删除此对象，因为未在 ObjectStateManager 中找到它。”
            //方法2
            //db1.Entry<users>(m).State = System.Data.Entity.EntityState.Deleted;
            db.SaveChanges();
        }
知识兔

ps：每次执行完之后记得SaveChanges()

仅供参考，有问题可评论指出。

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