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建设网站系统,软件推广的渠道是哪里找的,做阀门销售在哪个网站上做好,有什么做任务拿钱的网站以下是一个使用 .NET Core API 连接 MySQL 数据库实现简单记事本功能的完整示例，包含创建、读取、更新和删除（CRUD）操作。 1. 创建 .NET Core Web API 项目首先，打开命令行工具，使用以下命令创建一个新的 .NET Core…

以下是一个使用 .NET Core API 连接 MySQL 数据库实现简单记事本功能的完整示例，包含创建、读取、更新和删除（CRUD）操作。

1. 创建 .NET Core Web API 项目

首先，打开命令行工具，使用以下命令创建一个新的 .NET Core Web API 项目：

dotnet new webapi -n NotePadAPI
cd NotePadAPI

2. 安装 MySQL 数据库驱动

在项目目录下，使用以下命令安装 MySQL 数据库驱动：

dotnet add package MySqlConnector

3. 配置数据库连接字符串

打开 appsettings.json 文件，添加 MySQL 数据库连接字符串：

{"ConnectionStrings": {"DefaultConnection": "Server=localhost;Database=notepad;Uid=your_username;Pwd=your_password;"},"Logging": {"LogLevel": {"Default": "Information","Microsoft.AspNetCore": "Warning"}},"AllowedHosts": "*"
}

请将 your_username 和 your_password 替换为你的 MySQL 用户名和密码。

4. 创建数据库和表

在 MySQL 中创建一个名为 notepad 的数据库，并创建一个名为 notes 的表：

CREATE DATABASE notepad;USE notepad;CREATE TABLE notes (id INT AUTO_INCREMENT PRIMARY KEY,title VARCHAR(255) NOT NULL,content TEXT NOT NULL,created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

5. 创建数据模型

在 Models 文件夹下创建 Note.cs 文件：

using System;namespace NotePadAPI.Models
{public class Note{public int Id { get; set; }public string Title { get; set; }public string Content { get; set; }public DateTime CreatedAt { get; set; }}
}

6. 创建数据库上下文

在 Data 文件夹下创建 NoteContext.cs 文件：

using Microsoft.Data.SqlClient;
using MySqlConnector;
using NotePadAPI.Models;
using System.Collections.Generic;
using System.Data;namespace NotePadAPI.Data
{public class NoteContext{private readonly string _connectionString;public NoteContext(string connectionString){_connectionString = connectionString;}public List<Note> GetAllNotes(){var notes = new List<Note>();using (var connection = new MySqlConnection(_connectionString)){var query = "SELECT * FROM notes";var command = new MySqlCommand(query, connection);connection.Open();var reader = command.ExecuteReader();while (reader.Read()){notes.Add(new Note{Id = reader.GetInt32("id"),Title = reader.GetString("title"),Content = reader.GetString("content"),CreatedAt = reader.GetDateTime("created_at")});}reader.Close();}return notes;}public Note GetNoteById(int id){using (var connection = new MySqlConnection(_connectionString)){var query = "SELECT * FROM notes WHERE id = @id";var command = new MySqlCommand(query, connection);command.Parameters.AddWithValue("@id", id);connection.Open();var reader = command.ExecuteReader();if (reader.Read()){return new Note{Id = reader.GetInt32("id"),Title = reader.GetString("title"),Content = reader.GetString("content"),CreatedAt = reader.GetDateTime("created_at")};}reader.Close();}return null;}public void CreateNote(Note note){using (var connection = new MySqlConnection(_connectionString)){var query = "INSERT INTO notes (title, content) VALUES (@title, @content)";var command = new MySqlCommand(query, connection);command.Parameters.AddWithValue("@title", note.Title);command.Parameters.AddWithValue("@content", note.Content);connection.Open();command.ExecuteNonQuery();}}public void UpdateNote(Note note){using (var connection = new MySqlConnection(_connectionString)){var query = "UPDATE notes SET title = @title, content = @content WHERE id = @id";var command = new MySqlCommand(query, connection);command.Parameters.AddWithValue("@title", note.Title);command.Parameters.AddWithValue("@content", note.Content);command.Parameters.AddWithValue("@id", note.Id);connection.Open();command.ExecuteNonQuery();}}public void DeleteNote(int id){using (var connection = new MySqlConnection(_connectionString)){var query = "DELETE FROM notes WHERE id = @id";var command = new MySqlCommand(query, connection);command.Parameters.AddWithValue("@id", id);connection.Open();command.ExecuteNonQuery();}}}
}

7. 创建控制器

在 Controllers 文件夹下创建 NotesController.cs 文件：

using Microsoft.AspNetCore.Mvc;
using NotePadAPI.Data;
using NotePadAPI.Models;
using System.Collections.Generic;namespace NotePadAPI.Controllers
{[ApiController][Route("api/[controller]")]public class NotesController : ControllerBase{private readonly NoteContext _context;public NotesController(NoteContext context){_context = context;}[HttpGet]public ActionResult<IEnumerable<Note>> GetAllNotes(){var notes = _context.GetAllNotes();return Ok(notes);}[HttpGet("{id}")]public ActionResult<Note> GetNoteById(int id){var note = _context.GetNoteById(id);if (note == null){return NotFound();}return Ok(note);}[HttpPost]public ActionResult<Note> CreateNote(Note note){_context.CreateNote(note);return CreatedAtAction(nameof(GetNoteById), new { id = note.Id }, note);}[HttpPut("{id}")]public IActionResult UpdateNote(int id, Note note){if (id != note.Id){return BadRequest();}_context.UpdateNote(note);return NoContent();}[HttpDelete("{id}")]public IActionResult DeleteNote(int id){_context.DeleteNote(id);return NoContent();}}
}

8. 配置服务

打开 Program.cs 文件，配置数据库上下文：

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using NotePadAPI.Data;var builder = WebApplication.CreateBuilder(args);// Add services to the container.
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();// Configure database context
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
builder.Services.AddSingleton(new NoteContext(connectionString));var app = builder.Build();// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{app.UseSwagger();app.UseSwaggerUI();
}app.UseHttpsRedirection();app.UseAuthorization();app.MapControllers();app.Run();