将excel文件保存在应用程序文件夹中，并使用windows窗体和C#将内容上载到SQL Server

using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;

namespace ExcelToSQL
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnUpload_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Filter = "Excel Files|*.xlsx;*.xls";
            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                string filePath = openFileDialog.FileName;

                // 读取excel文件
                IWorkbook workbook;
                using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                {
                    workbook = new XSSFWorkbook(fileStream);
                }

                // 获取第一个工作表
                ISheet sheet = workbook.GetSheetAt(0);

                // 创建连接字符串
                string connectionString = "Data Source=YourServerName;Initial Catalog=YourDatabaseName;Integrated Security=True";

                // 建立与SQL Server的连接
                using (SqlConnection connection = new SqlConnection(connectionString))
                {
                    connection.Open();

                    // 遍历excel文件中的每一行
                    for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)
                    {
                        IRow row = sheet.GetRow(i);

                        // 读取每一列的数据
                        string column1 = row.GetCell(0).ToString();
                        string column2 = row.GetCell(1).ToString();
                        // ...

                        // 构建插入数据的SQL语句
                        string sql = $"INSERT INTO YourTableName (Column1, Column2) VALUES ('{column1}', '{column2}')";

                        // 执行插入操作
                        using (SqlCommand command = new SqlCommand(sql, connection))
                        {
                            command.ExecuteNonQuery();
                        }
                    }
                }

                MessageBox.Show("数据上传成功！");
            }
        }
    }
}