一、说明
这个例子是小白跟着学习代码记录，模拟用户登陆功能，并可以查询所有学生信息。
二、代码
共4个文件，如下
App.config
"1.0" encoding="utf-8" ?>"MyschoolConnectionString" connectionString="Data Source=.;Initial Catalog=Mydata;Persist Security Info=True;User ID=XLJ;Pooling=False;MultipleActiveResultSets=False;Encrypt=False;TrustServerCertificate=True;Password=123456;" /> "v4.0" sku=".NETFramework,Version=v4.7" />
Student.cs
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace Ado.NETDemo2 { ////// 学生实体类 /// public class Student { /// /// 编号 /// public string StudentNo { get; set; } /// /// 姓名 /// public string StudentName { get; set; } } }
StudentDao.cs
using System; using System.Collections.Generic; using System.Configuration; using System.Data.SqlClient; using System.Linq; using System.Text; using System.Threading.Tasks; namespace Ado.NETDemo2 { public class StudentDao { // 1、编写连接字符串 //string connectionString = "server=.;uid=XLJ;pwd=123456;database=Mydata;"; //string connectionString = "Data Source=.;Initial Catalog=Mydata;Persist Security Info=True;User ID=XLJ;Pooling=False;MultipleActiveResultSets=False;Encrypt=False;TrustServerCertificate=True;Password=123456;"; public static string connectionString = ConfigurationManager.ConnectionStrings["MyschoolConnectionString"].ToString(); // 2、建立连接 SqlConnection connection = new SqlConnection(connectionString); // connection.ConnectionString = connectionString; ////// 验证用户是否存在 /// /// /// /// /// public bool ValidataUser(string userName, string password, ref string message) { bool result = false; try { // 3、打开连接 connection.Open(); // Console.WriteLine("连接打开成功"); // 4、实现登陆功能 SqlCommand command = new SqlCommand(); //command.CommandText = string.Format("select count(*) from Student where StudentName='{0}' and LoginPwd='{1}'", userName, userPwd); //command.CommandText = $"select count(*) from Student where StudentName='{userName}' and LoginPwd='{password}'"; StringBuilder sb = new StringBuilder("select count(*) from Student"); sb.AppendFormat(" where StudentName='{0}' and LoginPwd='{1}'", userName, password); command.CommandText = sb.ToString(); command.Connection = connection; // 5、执行命令 int num = (int)command.ExecuteScalar(); if (num > 0) { result = true; message = "登陆成功"; } else { message = "用户名或者密码有误"; } } catch (SqlException sqlException) { Console.WriteLine("数据库访问异常~" + sqlException.Message); } catch (Exception ex) { Console.WriteLine("程序出现问题，请联系管理员。" + ex.Message); } finally { // 6、关闭连接 connection.Close(); //Console.WriteLine("连接关闭成功"); } return result; } /// /// 实现登陆获取邮箱 /// /// /// /// public string Login(string userName, string password) { // 2、建立连接 SqlConnection connection = new SqlConnection(connectionString); // connection.ConnectionString = connectionString; string result = string.Empty; try { // 3、打开连接 connection.Open(); // Console.WriteLine("连接打开成功"); // 4、实现登陆功能 SqlCommand command = new SqlCommand(); //command.CommandText = string.Format("select count(*) from Student where StudentName='{0}' and LoginPwd='{1}'", userName, userPwd); command.CommandText = $"select * from Student where StudentName='{userName}' and LoginPwd='{password}'"; command.Connection = connection; // 5、执行命令 SqlDataReader reader = command.ExecuteReader(); reader.Read(); result = reader["email"].ToString(); } catch (SqlException sqlException) { Console.WriteLine("数据库访问异常~" + sqlException.Message); } catch (Exception ex) { Console.WriteLine("程序出现问题，请联系管理员。" + ex.Message); } finally { // 6、关闭连接 connection.Close(); //Console.WriteLine("连接关闭成功"); } return result; } /// /// 获取所有学生 /// /// public List GetStudentList() { List students = new List (); StringBuilder sql = new StringBuilder("select StudentNo,StudentName from Student"); // 打开连接 connection.Open(); SqlCommand command = new SqlCommand(sql.ToString(), connection); SqlDataReader reader = command.ExecuteReader(); while (reader.Read()) { Student student = new Student(); student.StudentNo = reader["StudentNo"].ToString(); student.StudentName = reader["StudentName"].ToString(); // 组装到学生集合列表中 students.Add(student); } // 关闭读取器 reader.Close(); // 关闭连接 connection.Close(); return students; } } }
Program.cs
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace Ado.NETDemo2 { class Program { static void Main(string[] args) { Console.WriteLine("请输入用户名^_^"); string userName = Console.ReadLine(); Console.WriteLine("请输入密码o(*￣︶￣*)o"); string userPwd = Console.ReadLine(); StudentDao dao = new StudentDao(); string msg = string.Empty; if (dao.ValidataUser(userName, userPwd, ref msg)) { string email = dao.Login(userName, userPwd); Console.WriteLine("恭喜{0},{1}", email, msg); // 选择 Console.WriteLine("请选择"); int choice = int.Parse(Console.ReadLine()); switch (choice) { case 1: Console.WriteLine("统计学生人数"); break; case 2: Console.WriteLine("查询学生名单"); Liststudents = dao.GetStudentList(); foreach (var student in students) { Console.WriteLine(student.StudentName + "————" + student.StudentNo); } break; default: break; } } else { Console.WriteLine(msg); } } } }
三、效果
