三层架构补充

Posted 2020-10-24 西科之巅、不可能

第一、DAL、BLL、Model必须为类库，UI可以为控制台、winform、asp.net等；

第二、SqlHelper放在DAL中，但ConnectionString配置在UI的config中，这是因为ConfigurationManager是读取UI项目（入口启动项目）的config；

第三、Executescalar(),ExecuteReader()不仅可以用来执行select查询，还可以用来执行insert等操作；

第四、ADO.Net中想给SqlParameter的参数赋值null的话，必须传递Dbnull.Value;

第五、在c#代码中写sql语句bool类型数据必须写1或0；

 

案例：

 1 using SanCeng.Model;
 2 using System;
 3 using System.Collections.Generic;
 4 using System.Data;
 5 using System.Data.SqlClient;
 6 using System.Linq;
 7 using System.Text;
 8 using System.Threading.Tasks;
 9 
10 namespace SanCeng.DAL
11 {
12     public class UserDAL
13     {
14         /// <summary>
15         /// 新增
16         /// </summary>
17         /// <param name="userName"></param>
18         /// <param name="password"></param>
19         /// <param name="phoneNum"></param>
20         /// <param name="age"></param>
21         /// <returns></returns>
22         public long Add(string userName, string password, string phoneNum, int? age)
23         {
24            object obj = SqlHelper.ExecuteScalar("insert into T_Users(UserName,Password,PhoneNum,Age,IsDeleted) output inserted.id values(@UserName,@Password,@PhoneNum,@Age,0)", new SqlParameter("@UserName", userName), new SqlParameter("@Password", password), new SqlParameter("@PhoneNum", phoneNum),new SqlParameter("@Age",age==null?(object)DBNull.Value:age));
25             return Convert.ToInt64(obj);
26         }
27 
28         /// <summary>
29         /// 软删除id为主键的数据
30         /// </summary>
31         /// <param name="id"></param>
32         public void Delete(long id)
33         {
34             SqlHelper.ExecuteNonQuery("Update T_Users set IsDeleted=1 where [email protected]", new SqlParameter("@Id", id));
35         }
36         private User ToUser(DataRow row)
37         {
38             User user = new User();
39             user.Id = (long)row["Id"];
40             user.Age = row.IsNull("Age") ? null : (int?)row["Age"];
41             user.Password = (string)row["Password"];
42             user.IsDeleted = (bool)row["IsDeleted"];
43             user.phoneNum = (string)row["UserName"];
44             user.UserName = (string)row["UserName"];
45             return user;
46         }
47 
48         public void Update(User user)
49         {
50             SqlHelper.ExecuteNonQuery("Update T_Users set [email protected],[email protected],[email protected],[email protected] where [email protected]", new SqlParameter("@UserName", user.UserName), new SqlParameter("@Password", user.Password), new SqlParameter("@PhoneNum", user.phoneNum), new SqlParameter("@Age", user.Age == null ? (object)DBNull.Value : user.Age), new SqlParameter("@Id", user.Id));
51         }
52         public User GetById(long id)
53         {
54            DataTable table = SqlHelper.ExecuteQuery("select * from T_Users where [email protected]", new SqlParameter("@Id", id));
55             if(table.Rows.Count<=0)
56             {
57                 return null;
58             }
59             else if(table.Rows.Count>1)
60             {
61                 throw new ApplicationException("找到多条id="+id+"的数据");
62             }
63             else
64             {
65                 DataRow row = table.Rows[0];
66                 return ToUser(row);
67             }
68         }
69         /// <summary>
70         /// 返回所有未软删除的数据
71         /// </summary>
72         /// <returns></returns>
73         public IEnumerable<User> GetAll()
74         {
75             DataTable dt = SqlHelper.ExecuteQuery("select * fom T_User where IsDeleted = 0");
76             List<User> list = new List<User>();
77             foreach(DataRow row in dt.Rows)
78             {
79                 list.Add(ToUser(row));
80             }
81             return list;
82         }
83     }
84 
85 
86 
87 }

UserDAL

 

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Configuration;
 4 using System.Data;
 5 using System.Data.SqlClient;
 6 using System.Linq;
 7 using System.Text;
 8 using System.Threading.Tasks;
 9 
10 namespace SanCeng.DAL
11 {
12     class SqlHelper
13     {
14         private static string connStr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
15         public static  void ExecuteNonQuery(string sql, params SqlParameter[] parameters)
16         {
17             using (SqlConnection conn = new SqlConnection(connStr))
18             using (SqlCommand cmd = conn.CreateCommand())
19             {
20                 conn.Open();
21                 cmd.CommandText = sql;
22                 cmd.Parameters.AddRange(parameters);
23                 cmd.ExecuteNonQuery();
24             }
25         }
26         public static  object ExecuteScalar(string sql, params SqlParameter[] parameters)
27         {
28             using (SqlConnection conn = new SqlConnection(connStr))
29             using (SqlCommand cmd = conn.CreateCommand())
30             {
31                 conn.Open();
32                 cmd.CommandText = sql;
33                 cmd.Parameters.AddRange(parameters);
34                 return cmd.ExecuteScalar();
35             }
36         }
37         public static DataTable ExecuteQuery(string sql, params SqlParameter[] parameters)
38         {
39             DataTable table = new DataTable();
40             using (SqlConnection conn = new SqlConnection(connStr))
41             using (SqlCommand cmd = conn.CreateCommand())
42             {
43                 conn.Open();
44                 cmd.CommandText = sql;
45                 cmd.Parameters.AddRange(parameters);
46                 using (SqlDataReader reader = cmd.ExecuteReader())
47                 {
48                     table.Load(reader);
49                     return table;
50                 }
51             }
52         }
53     }
54 }

SqlHelper

 1 using SanCeng.DAL;
 2 using SanCeng.Model;
 3 using System;
 4 using System.Collections.Generic;
 5 using System.Linq;
 6 using System.Text;
 7 using System.Threading.Tasks;
 8 
 9 namespace SanCeng.BLL
10 {
11     public class UserBLL
12     {
13         private UserDAL uDAL = new UserDAL();
14         public long Add(string userName,string password,string phoneNum,int? age)
15         {
16             return uDAL.Add(userName, password, phoneNum, age);
17         }
18         public void Delete(long id)
19         {
20             uDAL.Delete(id);
21         }
22         public void Update(User user)
23         {
24             uDAL.Update(user);
25         }
26         public User GetById(long id)
27         {
28             return uDAL.GetById(id);
29         }
30         public IEnumerable<User> GetAll()
31         {
32             return uDAL.GetAll();
33         }
34     }
35 }

暂时的废物userBLL

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace SanCeng.Model
 8 {
 9     public class User
10     {
11         public long Id { get; set; }
12         public int? Age { get; set; }
13         public string phoneNum { get; set; }
14         public string Password { get; set; }
15         public bool IsDeleted { get; set; }
16         public string UserName { get; set; }
17     }
18 }

Model

 1 using SanCeng.BLL;
 2 using System;
 3 using System.Collections.Generic;
 4 using System.ComponentModel;
 5 using System.Data;
 6 using System.Drawing;
 7 using System.Linq;
 8 using System.Text;
 9 using System.Threading.Tasks;
10 using System.Windows.Forms;
11 
12 namespace SanCeng.WinForm
13 {
14     public partial class Form1 : Form
15     {
16         public Form1()
17         {
18             InitializeComponent();
19         }
20 
21         private void button1_Click(object sender, EventArgs e)
22         {
23             UserBLL bll = new UserBLL();
24             
25             bll.Delete(1);
26         }
27     }
28 }

UI