.net连接数据库教程

using System;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = "Server=your_server_name;Database=your_database_name;User Id=your_username;Password=your_password;";
        
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();
            Console.WriteLine("数据库连接成功！");

            string query = "SELECT * FROM your_table_name";
            SqlCommand command = new SqlCommand(query, connection);

            using (SqlDataReader reader = command.ExecuteReader())
            {
                while (reader.Read())
                {
                    Console.WriteLine(reader["column_name"].ToString());
                }
            }
        }
        Console.WriteLine("数据库连接关闭。");
    }
}

string query = "SELECT * FROM your_table_name WHERE id = @id";
SqlCommand command = new SqlCommand(query, connection);
command.Parameters.AddWithValue("@id", userId);