學習了如何編寫通用數據訪問類SQLHelper，在此基礎上還可以繼續優化程序，基於對象職責明確原則，將程序封裝成學生數據信息訪問類、班級信息訪問類、成績信息訪問類等。

 1     /// <summary>
 2     /// 學員信息數據訪問類
 3     /// </summary>
 4     class StudentService
 5     {
 6         public int AddStudent(string studentName, string gender, DateTime birthday,
 7             string stuIdNo, int
 
 age, string phoneNumber, string stuAddress, int classId)
 8         {
 9             string sql = "insert into Students(StudentName,Gender,Birthday,studentIdNo,Age,PhoneNumber,studentAddress, classId)";
10             sql += "values(‘{0}‘,‘{1}‘,‘{2}‘,{3},{4},‘{5}‘,‘{6}‘,{7})";
11             sql = string
 
.Format(sql, studentName, gender, birthday, stuIdNo, age, phoneNumber, stuAddress, classId);
12             return SQLHelper.Update(sql);
13         }
14      }

 1         static void Main(string[] args)
 2         {
 3             //獲取用戶輸入
 4             Console.WriteLine("請輸入學員姓名：");
 5             string
 
 stuName = Console.ReadLine();
 6             Console.WriteLine("請輸入學員性別：");
 7             string gender = Console.ReadLine();
 8             Console.WriteLine("請輸入學員出生日期：");
 9             DateTime birthday = Convert.ToDateTime(Console.ReadLine());
10             Console.WriteLine("請輸入學員身份證號：");
11             string stuIdNo = Console.ReadLine();
12             Console.WriteLine("請輸入學員年齡：");
13             int age = Convert.ToInt16(Console.ReadLine());
14             Console.WriteLine("請輸入學員電話：");
15             string phoneNumber = Console.ReadLine();
16             Console.WriteLine("請輸入學員身份地址：");
17             string stuAddress = Console.ReadLine();
18             Console.WriteLine("請輸入學員班級編號：");
19             int classId = Convert.ToInt16(Console.ReadLine());
20 
21             //調用數據訪問方法
22             StudentService objstuService = new StudentService();
23             int result = objstuService.AddStudent(stuName, gender, birthday, stuIdNo, age, phoneNumber, stuAddress, classId);
24             //展示結果
25             Console.WriteLine(result);
26             Console.ReadLine();
27         }

但是以上代碼存在缺點：方法參數多

1.定義和使用不方便，容易把參數寫錯

2.當對象是屬性變化時，方法的參數必須改變

問題解學辦法：使用實體類作為方法參數，穩定對外接口

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace ASP.NETDemo
 8 {
 9     /// <summary>
10     /// 學生實體類
11     /// </summary>
12     class Student
13     {
14         public int StudentId { get; set; }
15         public string StudentName { get; set; }
16         public string Gender { get; set; }
17         public DateTime Birthday { get; set; }
18         public decimal StudentIdNo { get; set; }
19         public int Age { get; set; }
20         public string PhoneNumber { get; set; }
21         public string StudentAddress { get; set; }
22         public int ClassId { get; set; }
23     }
24 }

優化後

1        public int AddStudent(Student objStudent)
2         {
3             string sql = "insert into Students(StudentName,Gender,Birthday,studentIdNo,Age,PhoneNumber,studentAddress, classId)";
4             sql += "values(‘{0}‘,‘{1}‘,‘{2}‘,{3},{4},‘{5}‘,‘{6}‘,{7})";
5             sql = string.Format(sql,objStudent.StudentName,objStudent.Gender,objStudent.Birthday,objStudent.StudentIdNo,objStudent.Age,objStudent.PhoneNumber,objStudent.StudentAddress, objStudent.ClassId);
6             return SQLHelper.Update(sql);
7         }

 1        static void Main(string[] args)
 2         {
 3             //創建學員對象
 4             Student objStu = new Student();
 5             
 6             //獲取用戶輸入,封裝學員對象
 7             Console.WriteLine("請輸入學員姓名：");
 8             objStu.StudentName = Console.ReadLine();
 9             Console.WriteLine("請輸入學員性別：");
10             objStu.Gender = Console.ReadLine();
11             Console.WriteLine("請輸入學員出生日期：");
12             objStu.Birthday = Convert.ToDateTime(Console.ReadLine());
13             Console.WriteLine("請輸入學員身份證號：");
14             objStu.StudentIdNo =Convert.ToDecimal( Console.ReadLine());
15             Console.WriteLine("請輸入學員年齡：");
16             objStu.Age = Convert.ToInt16(Console.ReadLine());
17             Console.WriteLine("請輸入學員電話：");
18             objStu.PhoneNumber = Console.ReadLine();
19             Console.WriteLine("請輸入學員身份地址：");
20             objStu.StudentAddress = Console.ReadLine();
21             Console.WriteLine("請輸入學員班級編號：");
22             objStu.ClassId = Convert.ToInt16(Console.ReadLine());
23 
24             //調用數據訪問方法
25             StudentService objstuService = new StudentService();
26             int result = objstuService.AddStudent(objStu);
27             //展示結果
28             Console.WriteLine(result);
29             Console.ReadLine();
30         }

基於對象職責明確原則優化程序