C#使用DataReader和CSV编写器批量/分块导出SQL Server大表

using System;
using System.Data;
using System.Data.SqlClient;
using System.IO;

public class Program
{
    public static void Main()
    {
        string connectionString = "Your SQL Server connection string";
        string query = "SELECT * FROM YourTable";
        string outputPath = "Your output CSV file path";

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            using (SqlCommand command = new SqlCommand(query, connection))
            {
                using (SqlDataReader reader = command.ExecuteReader())
                {
                    using (StreamWriter writer = new StreamWriter(outputPath))
                    {
                        // 写入CSV文件的表头
                        for (int i = 0; i < reader.FieldCount; i++)
                        {
                            writer.Write(reader.GetName(i));
                            if (i < reader.FieldCount - 1)
                            {
                                writer.Write(",");
                            }
                        }
                        writer.WriteLine();

                        // 逐行写入CSV文件的数据
                        while (reader.Read())
                        {
                            for (int i = 0; i < reader.FieldCount; i++)
                            {
                                writer.Write(reader[i]);
                                if (i < reader.FieldCount - 1)
                                {
                                    writer.Write(",");
                                }
                            }
                            writer.WriteLine();
                        }
                    }
                }
            }
        }

        Console.WriteLine("导出完成！");
    }
}