用c#导入excel 但是导入字段是服务器中数据来的

要用C#读取Excel文件并从服务器获取数据来填充Excel表格，可以按照以下步骤进行：

1.使用ExcelDataReader或NPOI等库读取Excel文件，将Excel数据保存在DataTable对象中。

using ExcelDataReader;
using System.Data;
using System.IO;

// open the Excel file for reading
using (var stream = File.Open(filePath, FileMode.Open, FileAccess.Read))
{
    using (var reader = ExcelReaderFactory.CreateReader(stream))
    {
        // load the data from the Excel file into a DataTable
        DataSet dataSet = reader.AsDataSet(new ExcelDataSetConfiguration()
        {
            ConfigureDataTable = (_) => new ExcelDataTableConfiguration()
            {
                UseHeaderRow = true
            }
        });
        DataTable dataTable = dataSet.Tables[0];
        
        // TODO: add code to retrieve data from the server and fill in the DataTable
    }
}

2.从服务器获取数据并填充DataTable对象，可以使用ADO.NET或其他数据访问库。

using System.Data.SqlClient;

// create a connection to the database
using (SqlConnection connection = new SqlConnection(connectionString))
{
    // open the database connection
    connection.Open();

    // create a SQL command to retrieve data from the database
    string sql = "SELECT * FROM MyTable";
    SqlCommand command = new SqlCommand(sql, connection);

    // execute the SQL command and fill a DataTable with the results
    SqlDataAdapter adapter = new SqlDataAdapter(command);
    DataTable dataTable = new DataTable();
    adapter.Fill(dataTable);

    // TODO: add code to merge the Excel data and the server data
}

3.将DataTable对象中的数据填充到Excel表格中。

using Excel = Microsoft.Office.Interop.Excel;

// create an Excel application object
Excel.Application excelApp = new Excel.Application();

// open the Excel workbook and worksheet
Excel.Workbook workbook = excelApp.Workbooks.Open(filePath);
Excel.Worksheet worksheet = workbook.Worksheets[1];

// loop through the rows of the DataTable and add the data to the Excel worksheet
int rowIndex = 2; // start on the second row, assuming the first row is a header row
foreach (DataRow row in dataTable.Rows)
{
    worksheet.Cells[rowIndex, 1] = row["Column1"]; // set the value of cell A(rowIndex) to the value of Column1 in the current row
    worksheet.Cells[rowIndex, 2] = row["Column2"]; // set the value of cell B(rowIndex) to the value of Column2 in the current row
    // TODO: add code to set the value of other cells in the current row
    rowIndex++;
}

// save and close the Excel workbook
workbook.Save();
workbook.Close();

// release resources
System.Runtime.InteropServices.Marshal.ReleaseComObject(worksheet);
System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
System.Runtime.InteropServices.Marshal.ReleaseComObject(excelApp);
worksheet = null;
workbook = null;
excelApp = null;

GC.Collect();