C# MySQL,VPS服务器搭建模板,深圳机房云主机,快速稳定美国vps,阿里的云主机

🗣 Wd提问: C# MySQL

🤖 Ai回答:
I'll help you with Cand MySQL integration、Here's a comprehensive guide covering the basics:

1、Installation and Setup

Install MySQL Connector/NET
bash
Using NuGet Package Manager Console
Install-Package MySql.Data

Or using .NET CLI
dotnet add package MySql.Data

2、Basic Connection Example

csharp
using System;
using MySql.Data.MySqlClient;

class Program
{
static void Main()
{
string connectionString = Server=localhost;Database=testdb;Uid=root;Pwd=yourpassword;;

try
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
connection.Open();
Console.WriteLine(Connection successful!);

// Your database operations here
}
}
catch (Exception ex)
{
Console.WriteLine($Error: {ex.Message});
}
}
}

3、CRUD Operations Example

csharp
using System;
using System.Collections.Generic;
using MySql.Data.MySqlClient;

public class User
{
public int Id { get; set; }
public string Name { get; set; }
public string Email { get; set; }
}

public class DatabaseManager
{
private string connectionString = Server=localhost;Database=testdb;Uid=root;Pwd=yourpassword;;

// Create
public bool CreateUser(User user)
{
string query = INSERT INTO users (name, email) VALUES (@name, @email);

using (MySqlConnection connection = new MySqlConnection(connectionString))
{
try
{
connection.Open();
using (MySqlCommand command = new MySqlCommand(query, connection))
{
command.Parameters.AddWithValue(@name, user.Name);
command.Parameters.AddWithValue(@email, user.Email);

int rowsAffected = command.ExecuteNonQuery();
return rowsAffected 0;
}
}
catch (Exception ex)
{
Console.WriteLine($Error: {ex.Message});
return false;
}
}
}

// Read
public List<User GetAllUsers()
{
List<User users = new List<User();
string query = SELECT id, name, email FROM users;

using (MySqlConnection connection = new MySqlConnection(connectionString))
{
try
{
connection.Open();
using (MySqlCommand command = new MySqlCommand(query, connection))
{
using (MySqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
users.Add(new User
{
Id = reader.GetInt32(id),
Name = reader.GetString(name),
Email = reader.GetString(email)
});
}
}
}
}
catch (Exception ex)
{
Console.WriteLine($Error: {ex.Message});
}
}

return users;
}

// Update
public bool UpdateUser(int id, User user)
{
string query = UPDATE users SET name = @name, email = @email WHERE id = @id;

using (MySqlConnection connection = new MySqlConnection(connectionString))
{
try
{
connection.Open();
using (MySqlCommand command = new MySqlCommand(query, connection))
{
command.Parameters.AddWithValue(@name, user.Name);
command.Parameters.AddWithValue(@email, user.Email);
command.Parameters.AddWithValue(@id, id);

int rowsAffected = command.ExecuteNonQuery();
return rowsAffected 0;
}
}
catch (Exception ex)
{
Console.WriteLine($Error: {ex.Message});
return false;
}
}
}

// Delete
public bool DeleteUser(int id)
{
string query = DELETE FROM users WHERE id = @id;

using (MySqlConnection connection = new MySqlConnection(connectionString))
{
try
{
connection.Open();
using (MySqlCommand command = new MySqlCommand(query, connection))
{
command.Parameters.AddWithValue(@id, id);

int rowsAffected = command.ExecuteNonQuery();
return rowsAffected 0;
}
}
catch (Exception ex)
{
Console.WriteLine($Error: {ex.Message});
return false;
}
}
}
}

4、Using Entity Framework Core with MySQL

Install Packages
bash
dotnet add package Pomelo.EntityFrameworkCore.MySql

Model Class
csharp
public class User
{
public int Id { get; set; }
public string Name { get; set; }
public string Email { get; set; }
}

DbContext
csharp
using Microsoft.EntityFrameworkCore;

public class ApplicationDbContext : DbContext
{
public DbSet<User Users { get; set; }

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseMySql(
Server=localhost;Database=testdb;Uid=root;Pwd=yourpassword;,
ServerVersion.AutoDetect(Server=localhost;Database=testdb;Uid=root;Pwd=yourpassword;)
);
}
}

Usage
csharp
using (var context = new ApplicationDbContext())
{
// Add user
var user = new User { Name = John Doe, Email = john@65.hk };
context.Users.Add(user);
context.SaveChanges();

// Get all users
var users = context.Users.ToList();

// Update user
var userToUpdate = context.Users.First();
userToUpdate.Name = Jane Doe;
context.SaveChanges();

// Delete user
context.Users.Remove(userToUpdate);
context.SaveChanges();
}

5、Connection Pooling Example

csharp
public class DatabaseHelper
{
private static readonly string ConnectionString =
Server=localhost;Database=testdb;Uid=root;Pwd=yourpassword;Pooling=true;MinPoolSize=5;MaxPoolSize=20;;

public static async Task<T ExecuteQueryAsync<T(Func<MySqlConnection, T operation)
{
using (var connection = new MySqlConnection(ConnectionString))
{
await connection.OpenAsync();
return operation(connection);
}
}

public static async Task ExecuteNonQueryAsync(string query, params (string name, object value)[] parameters)
{
await ExecuteQueryAsync(async connection =
{
using (var command = new MySqlCommand(query, connection))
{
foreach (var param in parameters)
{
command.Parameters.AddWithValue(param.name, param.value);
}
await command.ExecuteNonQueryAsync();
}
});
}
}

6、Configuration File Approach

Create `appsettings.json`:
json
{
ConnectionStrings: {
DefaultConnection: Server=localhost;Database=testdb;Uid=root;Pwd=yourpassword;
}
}

Read configuration:
csharp
using Microsoft.Extensions.Configuration;

public class ConfigManager
{
private static IConfiguration _configuration;

static ConfigManager()
{
_configuration = new ConfigurationBuilder()
.AddJsonFile(appsettings.json)
.Build();
}

public static string GetConnectionString()
{
return _configuration.GetConnectionString(DefaultConnection);
}
}

7、Error Handling Best Practices

csharp
public async Task<bool SafeDatabaseOperationAsync(Func<MySqlConnection, Task operation)
{
try
{
using (var connection = new MySqlConnection(connectionString))
{
await connection.OpenAsync();
await operation(connection);
return true;
}
}
catch (MySqlException ex)
{
// Handle specific MySQL errors
switch (ex.Number)
{
case 1045: // Access denied
Console.WriteLine(Access denied check credentials);
break;
case 2003: // Can't connect to MySQL server
Console.WriteLine(Cannot connect to database server);
break;
default:
Console.WriteLine($MySQL Error: {ex.Message});
break;
}
return false;
}
catch (Exception ex)
{
Console.WriteLine($General error: {ex.Message});
return false;
}
}

Key Points to Remember:

1、Always use `using` statements for proper resource disposal
2、Use parameterized queries to prevent SQL injection
3、Handle exceptions appropriately
4、Consider connection pooling for better performance
5、Validate input data before database operations
6、Use async methods for better scalability

Would you like me to elaborate on any specific aspect of Cand MySQL integration?

Ai作答

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