Visual Studio 2022连接mysql数据库3，利用Entity Framework Core技术实现一个表的CRUD
注意
关于VS中用ODBC连接mysql数据库，可参考我的这篇文章：https://www.cnblogs.com/ztn195/p/19144339
关于VS中用 ADO.NET来操作数据库，可参考我的这篇文章：https://www.cnblogs.com/ztn195/p/19148337
首先在VS 2022中可以新建两种C#桌面应用的项目：
Windows 窗体应用 (支持.NET 8.0) 创建的是现代、跨平台的新式项目。
Windows 窗体应用(.NET Framework) 创建的是传统、仅限Windows的旧式项目。
而想要用利用Entity Framework Core技术则必须采用支持.NET 8.0的Windows 窗体应用。
创建支持.NET 8.0的Windows 窗体应用
直接在VS2022中建就好了（上方图片中的第一个）。
安装依赖
安装下方图片的三个就好了
# 安装MySQL EF Core提供程序 Install-Package Pomelo.EntityFrameworkCore.MySql
具体代码
Student
查看代码
namespace 测试1.Models
{
/// <summary>
/// 学生实体类
/// </summary>
public class Student
{
/// <summary>
/// 学生ID（主键，自增）
/// </summary>
public int Id { get; set; }
/// <summary>
/// 学生姓名
/// </summary>
public string Name { get; set; }
/// <summary>
/// 学生年龄
/// </summary>
public int Age { get; set; }
/// <summary>
/// 性别
/// </summary>
public string Gender { get; set; }
/// <summary>
/// 专业
/// </summary>
public string Major { get; set; }
/// <summary>
/// 入学日期
/// </summary>
public DateTime AdmissionDate { get; set; }
}
}StudentDbContext
查看代码
using Microsoft.EntityFrameworkCore;
using 测试1.Models;
namespace 测试1.DataAccess
{
/// <summary>
/// 学生数据库上下文
/// </summary>
public class StudentDbContext : DbContext
{
/// <summary>
/// 学生表
/// </summary>
public DbSet<Student> Students { get; set; }
/// <summary>
/// 配置数据库连接
/// </summary>
/// <param name="optionsBuilder"></param>
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
string connectionString = "server=localhost;user=root;password=;database=studentdb;";
optionsBuilder.UseMySql(connectionString, ServerVersion.AutoDetect(connectionString));
}
/// <summary>
/// 配置实体映射
/// </summary>
/// <param name="modelBuilder"></param>
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
// 指定表名
modelBuilder.Entity<Student>().ToTable("student");
// 配置主键
modelBuilder.Entity<Student>().HasKey(s => s.Id);
// 配置字段映射和属性
modelBuilder.Entity<Student>()
.Property(s => s.Name)
.HasColumnName("name")
.HasMaxLength(100)
.IsRequired();
modelBuilder.Entity<Student>()
.Property(s => s.Age)
.HasColumnName("age")
.IsRequired();
modelBuilder.Entity<Student>()
.Property(s => s.Gender)
.HasColumnName("gender")
.HasMaxLength(10)
.IsRequired();
modelBuilder.Entity<Student>()
.Property(s => s.Major)
.HasColumnName("major")
.HasMaxLength(100)
.IsRequired();
modelBuilder.Entity<Student>()
.Property(s => s.AdmissionDate)
.HasColumnName("admission_date")
.HasColumnType("date")
.IsRequired();
}
}
}StudentRepository
查看代码
using 测试1.Models;
using System.Collections.Generic;
using System.Linq;
namespace 测试1.DataAccess
{
/// <summary>
/// 学生数据访问类
/// </summary>
public class StudentRepository
{
private readonly StudentDbContext _context;
/// <summary>
/// 构造函数
/// </summary>
public StudentRepository()
{
_context = new StudentDbContext();
}
/// <summary>
/// 获取所有学生
/// </summary>
public List<Student> GetAllStudents()
{
return _context.Students.ToList();
}
/// <summary>
/// 根据ID获取学生
/// </summary>
public Student GetStudentById(int id)
{
return _context.Students.FirstOrDefault(s => s.Id == id);
}
/// <summary>
/// 添加学生
/// </summary>
public void AddStudent(Student student)
{
_context.Students.Add(student);
_context.SaveChanges();
}
/// <summary>
/// 更新学生信息
/// </summary>
public void UpdateStudent(Student student)
{
_context.Students.Update(student);
_context.SaveChanges();
}
/// <summary>
/// 删除学生
/// </summary>
public void DeleteStudent(int id)
{
var student = _context.Students.FirstOrDefault(s => s.Id == id);
if (student != null)
{
_context.Students.Remove(student);
_context.SaveChanges();
}
}
}
}StudentService
查看代码
using 测试1.DataAccess;
using 测试1.Models;
using System.Collections.Generic;
using System;
namespace 测试1.Business
{
/// <summary>
/// 学生业务逻辑类
/// </summary>
public class StudentService
{
private readonly StudentRepository _studentRepository;
/// <summary>
/// 构造函数
/// </summary>
public StudentService()
{
_studentRepository = new StudentRepository();
}
/// <summary>
/// 获取所有学生
/// </summary>
public List<Student> GetAllStudents()
{
return _studentRepository.GetAllStudents();
}
/// <summary>
/// 根据ID获取学生
/// </summary>
public Student GetStudentById(int id)
{
return _studentRepository.GetStudentById(id);
}
/// <summary>
/// 添加学生
/// </summary>
public void AddStudent(Student student)
{
// 业务逻辑验证
if (string.IsNullOrEmpty(student.Name))
throw new ArgumentException("学生姓名不能为空");
if (student.Age < 16 || student.Age > 30)
throw new ArgumentException("学生年龄应在16-30岁之间");
if (string.IsNullOrEmpty(student.Gender) || (student.Gender != "男" && student.Gender != "女"))
throw new ArgumentException("性别只能是'男'或'女'");
if (string.IsNullOrEmpty(student.Major))
throw new ArgumentException("专业不能为空");
_studentRepository.AddStudent(student);
}
/// <summary>
/// 更新学生信息
/// </summary>
public void UpdateStudent(Student student)
{
// 业务逻辑验证
if (string.IsNullOrEmpty(student.Name))
throw new ArgumentException("学生姓名不能为空");
if (student.Age < 16 || student.Age > 30)
throw new ArgumentException("学生年龄应在16-30岁之间");
if (string.IsNullOrEmpty(student.Gender) || (student.Gender != "男" && student.Gender != "女"))
throw new ArgumentException("性别只能是'男'或'女'");
if (string.IsNullOrEmpty(student.Major))
throw new ArgumentException("专业不能为空");
_studentRepository.UpdateStudent(student);
}
/// <summary>
/// 删除学生
/// </summary>
public void DeleteStudent(int id)
{
_studentRepository.DeleteStudent(id);
}
}
}Form1
查看代码
using 测试1.Business;
using 测试1.Models;
using System;
using System.Windows.Forms;
using System.Data;
namespace 测试1
{
public partial class Form1 : Form
{
private readonly StudentService _studentService;
public Form1()
{
InitializeComponent();
_studentService = new StudentService();
}
private void Form1_Load(object sender, EventArgs e)
{
LoadStudentData();
}
private void LoadStudentData()
{
try
{
var students = _studentService.GetAllStudents();
dataGridViewStudents.DataSource = students;
}
catch (Exception ex)
{
MessageBox.Show("加载数据失败: " + ex.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void ClearInputs()
{
txtName.Text = "";
txtAge.Text = "";
txtGender.Text = "男";
txtMajor.Text = "";
dtpAdmissionDate.Value = DateTime.Now;
}
private void dataGridViewStudents_SelectionChanged(object sender, EventArgs e)
{
if (dataGridViewStudents.SelectedRows.Count > 0)
{
var selectedRow = dataGridViewStudents.SelectedRows[0];
txtName.Text = selectedRow.Cells["Id"].OwningColumn.DataPropertyName == "Id" ?
selectedRow.Cells["NameColumn"].Value.ToString() :
selectedRow.Cells["Name"].Value.ToString();
txtAge.Text = selectedRow.Cells["Id"].OwningColumn.DataPropertyName == "Id" ?
selectedRow.Cells["AgeColumn"].Value.ToString() :
selectedRow.Cells["Age"].Value.ToString();
txtGender.Text = selectedRow.Cells["Id"].OwningColumn.DataPropertyName == "Id" ?
selectedRow.Cells["GenderColumn"].Value.ToString() :
selectedRow.Cells["Gender"].Value.ToString();
txtMajor.Text = selectedRow.Cells["Id"].OwningColumn.DataPropertyName == "Id" ?
selectedRow.Cells["MajorColumn"].Value.ToString() :
selectedRow.Cells["Major"].Value.ToString();
dtpAdmissionDate.Value = selectedRow.Cells["Id"].OwningColumn.DataPropertyName == "Id" ?
Convert.ToDateTime(selectedRow.Cells["AdmissionDateColumn"].Value) :
Convert.ToDateTime(selectedRow.Cells["AdmissionDate"].Value);
}
}
private void btnAdd_Click(object sender, EventArgs e)
{
try
{
// 验证输入
if (string.IsNullOrEmpty(txtName.Text))
{
MessageBox.Show("请输入学生姓名", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtName.Focus();
return;
}
if (!int.TryParse(txtAge.Text, out int age) || age < 16 || age > 30)
{
MessageBox.Show("请输入有效的年龄（16-30岁）", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtAge.Focus();
return;
}
if (string.IsNullOrEmpty(txtGender.Text) || (txtGender.Text != "男" && txtGender.Text != "女"))
{
MessageBox.Show("性别只能是'男'或'女'", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtGender.Focus();
return;
}
if (string.IsNullOrEmpty(txtMajor.Text))
{
MessageBox.Show("请输入专业", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtMajor.Focus();
return;
}
var student = new Student
{
Name = txtName.Text,
Age = age,
Gender = txtGender.Text,
Major = txtMajor.Text,
AdmissionDate = dtpAdmissionDate.Value
};
_studentService.AddStudent(student);
LoadStudentData();
ClearInputs();
MessageBox.Show("添加成功！", "成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
catch (Exception ex)
{
MessageBox.Show("添加失败: " + ex.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void btnUpdate_Click(object sender, EventArgs e)
{
try
{
if (dataGridViewStudents.SelectedRows.Count > 0)
{
var selectedRow = dataGridViewStudents.SelectedRows[0];
int studentId = (int)selectedRow.Cells["Id"].Value;
// 验证输入
if (string.IsNullOrEmpty(txtName.Text))
{
MessageBox.Show("请输入学生姓名", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtName.Focus();
return;
}
if (!int.TryParse(txtAge.Text, out int age) || age < 16 || age > 30)
{
MessageBox.Show("请输入有效的年龄（16-30岁）", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtAge.Focus();
return;
}
if (string.IsNullOrEmpty(txtGender.Text) || (txtGender.Text != "男" && txtGender.Text != "女"))
{
MessageBox.Show("性别只能是'男'或'女'", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtGender.Focus();
return;
}
if (string.IsNullOrEmpty(txtMajor.Text))
{
MessageBox.Show("请输入专业", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
txtMajor.Focus();
return;
}
var student = new Student
{
Id = studentId,
Name = txtName.Text,
Age = age,
Gender = txtGender.Text,
Major = txtMajor.Text,
AdmissionDate = dtpAdmissionDate.Value
};
_studentService.UpdateStudent(student);
LoadStudentData();
ClearInputs();
MessageBox.Show("更新成功！", "成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else
{
MessageBox.Show("请先选择要更新的学生记录", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
}
catch (Exception ex)
{
MessageBox.Show("更新失败: " + ex.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void btnDelete_Click(object sender, EventArgs e)
{
try
{
if (dataGridViewStudents.SelectedRows.Count > 0)
{
var selectedRow = dataGridViewStudents.SelectedRows[0];
var studentId = (int)selectedRow.Cells["Id"].Value;
if (MessageBox.Show("确定要删除这条记录吗？", "确认删除", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
{
_studentService.DeleteStudent(studentId);
LoadStudentData();
ClearInputs();
MessageBox.Show("删除成功！", "成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}
else
{
MessageBox.Show("请先选择要删除的学生记录", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
}
catch (Exception ex)
{
MessageBox.Show("删除失败: " + ex.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void btnRefresh_Click(object sender, EventArgs e)
{
LoadStudentData();
}
private void btnClear_Click(object sender, EventArgs e)
{
ClearInputs();
}
}
}项目结构与运行结果
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