EF 的 CURD 操作

 1         /// <summary> 2         /// 添加 3         /// </summary> 4         /// <returns></returns> 5         public static int Add() 6         { 7             using (var db = new NorthwindEntities()) 8             { 9                 var customer = new Customers()10                 {11                     CustomerID = "fanguza",12                     Address = "地球",13                     City = "广东",14                     Phone = "13800138000",15                     CompanyName = "博客园",16                     ContactName = "反骨仔"17                 };18 19                 //方法一20                 //db.Customers.Add(customer);21 22                 //方法二23                 var entry = db.Entry(customer);24                 entry.State = EntityState.Added;25 26                 return db.SaveChanges();27             }28         }

 1         /// <summary> 2         /// 删除 3         /// </summary> 4         /// <returns></returns> 5         static int Delete() 6         { 7             using (var db = new NorthwindEntities()) 8             { 9                 var customer = new Customers()10                 {11                     CustomerID = "fanguzi"12                 };13 14                 db.Customers.Attach(customer);15                 db.Customers.Remove(customer);16 17                 return db.SaveChanges();18             }19         }

 1         /// <summary> 2         /// 编辑（修改） 3         /// </summary> 4         /// <returns></returns> 5         static int Edit() 6         { 7             using (var db = new NorthwindEntities()) 8             { 9                 var customer = db.Customers.FirstOrDefault(u => u.CustomerID == "fanguzai");10 11                 if (customer == null)12                 {13                     return 0;14                 }15 16                 customer.ContactName = "erwuzai";17                 return db.SaveChanges();18             }19         }

 1         /// <summary> 2         /// 查询 3         /// </summary> 4         static Customers Query() 5         { 6             using (var db = new NorthwindEntities()) 7             { 8                 var query = 9                     db.Customers.Where(u => u.ContactName == "fanguza").OrderBy(u => u.ContactName).Take(1);10 11                 return query.FirstOrDefault();12             }13         }

 1         public IQueryable<Customers> GetPageOfCustomerses<TKey>(int pageIndex, int pageSize, 2             Expression<Func<Customers, bool>> wherExpression, 3             Expression<Func<Customers, TKey>> orderByExpression) 4         { 5             using (var db = new NorthwindEntities()) 6             { 7                 //分页前需要排序 8                 return db.Customers.Where(wherExpression).OrderBy(orderByExpression).Skip((pageIndex - 1) * pageSize).Take(pageSize); 9             }10         }

 1         static void BatchAdd() 2         { 3             using (var db = new NorthwindEntities()) 4             { 5                 for (var i = 0; i < 50; i++) 6                 { 7                     var customer = new Customers() 8                     { 9                         CustomerID = "fanguzai" + i,10                         Address = "中国",11                         City = "广州",12                         Phone = "13800138000" + i,13                         CompanyName = "阳春一中",14                         ContactName = "反骨仔" + i15                     };16 17                     db.Customers.Add(customer);18                 }19 20                 db.SaveChanges();21             }22         }

1         public IQueryable<Customers> GetCustomerses<TKey>(Expression<Func<Customers, bool>> whereExpression,2             Expression<Func<Customers, TKey>> orderExpression)3         {4             using (var db = new NorthwindEntities())5             {6                 return db.Customers.Where(whereExpression).OrderBy(orderExpression);7             }8         }