.net8 winform程序使用EntityFrameworkCore連接數據庫

在.NET 8 WinForms應用程序中使用Entity Framework (EF) Core，你需要按照以下步驟操作：
1.添加Entity Framework Core NuGet包。
2.定義你的數據模型。
3.創建數據庫上下文 (DbContext)。
4.在數據庫上下文中配置Entity Framework。
5.使用Entity Framework Core的API來執行數據庫操作。
以下是一個簡單的示例：

安裝Entity Framework Core NuGet包：
連接sqlserver數據庫
dotnet add package Microsoft.EntityFrameworkCore
dotnet add package Microsoft.EntityFrameworkCore.SqlServer
dotnet add package Microsoft.EntityFrameworkCore.Tools

連接Mysql數據庫
dotnet add package Microsoft.EntityFrameworkCore
dotnet add package Pomelo.EntityFrameworkCore.MySql
dotnet add package Microsoft.EntityFrameworkCore.Tools

定義數據模型：

using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;

namespace WinFormsApp.Models
{
    [Table("student")]
    public class Student
    {
        /// <summary>
        /// 主鍵，自增
        /// </summary>
        [Key, Column("id"), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int Id { get; set; }
        [Column("last_name"), StringLength(50)]
        public string LastName { get; set; } = string.Empty;
        [Column("first_mid_name"),StringLength(50)]
        public string FirstMidName { get; set; } = string.Empty;
        [Column("enrollment_date")]
        public DateTime EnrollmentDate { get; set; }
    }
}

創建數據庫上下文：

using System.Configuration;
using Microsoft.EntityFrameworkCore;
using WinFormsApp.Models;

namespace WinFormsApp
{
    public class XCGDbContext : DbContext
    {
        public DbSet<Student> Students { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            //連接mysql，需要安裝 Pomelo.EntityFrameworkCore.MySql
            string connStr = ConfigurationManager.ConnectionStrings["MysqlContext"] + "";
            var serverVersion = ServerVersion.AutoDetect(connStr);
            optionsBuilder.UseMySql(connStr, serverVersion);

            //連接sql，需要安裝 Microsoft.EntityFrameworkCore.SqlServer
            //optionsBuilder.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Blogging;Integrated Security=True");
        }
    }
}

在winform程序中使用EF Core：

using (var context = new XCGDbContext())
{
    // 添加
    context.Students.Add(new Student { EnrollmentDate = DateTime.Now, FirstMidName = "jay" + DateTime.Now.Ticks, LastName = "x" });
    context.SaveChanges();

    // 查詢
    var stus = context.Students.ToList();

    // 更新
    foreach (var stu in stus)
    {
        stu.LastName = "star";
    }
    context.SaveChanges();

    // 刪除
    var stuToDelete = context.Students.FirstOrDefault();
    context.Students.Remove(stuToDelete);
    context.SaveChanges();
}

使用以下命令來創建和應用數據庫遷移：
dotnet ef migrations add InitialCreate
dotnet ef database update