Interop とIronXLを使用して C# で DataTable を Excel にエクスポートする方法

using Microsoft.Office.Interop.Excel;
using System.Data;
using System.Runtime.InteropServices;

// Create a sample DataTable with employee data
DataTable dt = new DataTable("Employees");
dt.Columns.Add("EmployeeID", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Department", typeof(string));
dt.Columns.Add("Salary", typeof(decimal));

dt.Rows.Add(1, "John Smith", "Engineering", 75000);
dt.Rows.Add(2, "Sarah Johnson", "Marketing", 65000);
dt.Rows.Add(3, "Michael Chen", "Finance", 70000);
dt.Rows.Add(4, "Emily Davis", "Engineering", 80000);

// Initialize Excel Application object
Application excelApp = new Application
{
    Visible = false,
    DisplayAlerts = false
};

Workbook workbook = excelApp.Workbooks.Add();
Worksheet worksheet = (Worksheet)workbook.ActiveSheet;

try
{
    // Write column headers to the first row
    for (int i = 0; i < dt.Columns.Count; i++)
    {
        worksheet.Cells[1, i + 1] = dt.Columns[i].ColumnName;
    }

    // Write data rows starting from row 2
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        for (int j = 0; j < dt.Columns.Count; j++)
        {
            worksheet.Cells[i + 2, j + 1] = dt.Rows[i][j].ToString();
        }
    }

    string filePath = @"C:\Reports\EmployeeReport_Interop.xlsx";
    workbook.SaveAs(filePath);
    Console.WriteLine("Excel file created using Interop.");
}
catch (Exception ex)
{
    Console.WriteLine("Error: " + ex.Message);
}
finally
{
    // Always release COM objects to prevent orphaned Excel processes
    workbook.Close();
    excelApp.Quit();
    Marshal.ReleaseComObject(worksheet);
    Marshal.ReleaseComObject(workbook);
    Marshal.ReleaseComObject(excelApp);
}

Imports Microsoft.Office.Interop.Excel
Imports System.Data
Imports System.Runtime.InteropServices

' Create a sample DataTable with employee data
Dim dt As New DataTable("Employees")
dt.Columns.Add("EmployeeID", GetType(Integer))
dt.Columns.Add("Name", GetType(String))
dt.Columns.Add("Department", GetType(String))
dt.Columns.Add("Salary", GetType(Decimal))

dt.Rows.Add(1, "John Smith", "Engineering", 75000)
dt.Rows.Add(2, "Sarah Johnson", "Marketing", 65000)
dt.Rows.Add(3, "Michael Chen", "Finance", 70000)
dt.Rows.Add(4, "Emily Davis", "Engineering", 80000)

' Initialize Excel Application object
Dim excelApp As New Application With {
    .Visible = False,
    .DisplayAlerts = False
}

Dim workbook As Workbook = excelApp.Workbooks.Add()
Dim worksheet As Worksheet = CType(workbook.ActiveSheet, Worksheet)

Try
    ' Write column headers to the first row
    For i As Integer = 0 To dt.Columns.Count - 1
        worksheet.Cells(1, i + 1) = dt.Columns(i).ColumnName
    Next

    ' Write data rows starting from row 2
    For i As Integer = 0 To dt.Rows.Count - 1
        For j As Integer = 0 To dt.Columns.Count - 1
            worksheet.Cells(i + 2, j + 1) = dt.Rows(i)(j).ToString()
        Next
    Next

    Dim filePath As String = "C:\Reports\EmployeeReport_Interop.xlsx"
    workbook.SaveAs(filePath)
    Console.WriteLine("Excel file created using Interop.")
Catch ex As Exception
    Console.WriteLine("Error: " & ex.Message)
Finally
    ' Always release COM objects to prevent orphaned Excel processes
    workbook.Close()
    excelApp.Quit()
    Marshal.ReleaseComObject(worksheet)
    Marshal.ReleaseComObject(workbook)
    Marshal.ReleaseComObject(excelApp)
End Try

using IronXL;
using System.Data;

// Create a sample DataTable
DataTable dt = new DataTable("Employees");
dt.Columns.Add("EmployeeID", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Department", typeof(string));
dt.Columns.Add("Salary", typeof(decimal));

dt.Rows.Add(1, "John Smith", "Engineering", 75000);
dt.Rows.Add(2, "Sarah Johnson", "Marketing", 65000);
dt.Rows.Add(3, "Michael Chen", "Finance", 70000);
dt.Rows.Add(4, "Emily Davis", "Engineering", 80000);

// Create a new Excel workbook
WorkBook workbook = WorkBook.Create(ExcelFileFormat.XLSX);
WorkSheet sheet = workbook.CreateWorkSheet("Employees");

// Write column headers to row 0
for (int i = 0; i < dt.Columns.Count; i++)
{
    sheet.SetCellValue(0, i, dt.Columns[i].ColumnName);
}

// Export DataTable rows to Excel cells
for (int i = 0; i < dt.Rows.Count; i++)
{
    for (int j = 0; j < dt.Columns.Count; j++)
    {
        sheet.SetCellValue(i + 1, j, dt.Rows[i][j]);
    }
}

string filePath = @"C:\Reports\EmployeeReport_IronXL.xlsx";
workbook.SaveAs(filePath);
Console.WriteLine("Excel file created using IronXL.");

Imports IronXL
Imports System.Data

' Create a sample DataTable
Dim dt As New DataTable("Employees")
dt.Columns.Add("EmployeeID", GetType(Integer))
dt.Columns.Add("Name", GetType(String))
dt.Columns.Add("Department", GetType(String))
dt.Columns.Add("Salary", GetType(Decimal))

dt.Rows.Add(1, "John Smith", "Engineering", 75000)
dt.Rows.Add(2, "Sarah Johnson", "Marketing", 65000)
dt.Rows.Add(3, "Michael Chen", "Finance", 70000)
dt.Rows.Add(4, "Emily Davis", "Engineering", 80000)

' Create a new Excel workbook
Dim workbook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workbook.CreateWorkSheet("Employees")

' Write column headers to row 0
For i As Integer = 0 To dt.Columns.Count - 1
    sheet.SetCellValue(0, i, dt.Columns(i).ColumnName)
Next

' Export DataTable rows to Excel cells
For i As Integer = 0 To dt.Rows.Count - 1
    For j As Integer = 0 To dt.Columns.Count - 1
        sheet.SetCellValue(i + 1, j, dt.Rows(i)(j))
    Next
Next

Dim filePath As String = "C:\Reports\EmployeeReport_IronXL.xlsx"
workbook.SaveAs(filePath)
Console.WriteLine("Excel file created using IronXL.")

using IronXL;
using IronXL.Styles;
using System;
using System.Data;
using System.IO;

// --- ExcelExporter helper ---

bool ExportToExcel(DataTable dt, string filePath)
{
    if (dt == null || dt.Rows.Count == 0)
        return false;

    try
    {
        WorkBook workbook = WorkBook.Create(ExcelFileFormat.XLSX);
        WorkSheet sheet = workbook.CreateWorkSheet(dt.TableName ?? "Sheet1");

        // Bold headers in the first row
        for (int i = 0; i < dt.Columns.Count; i++)
        {
            var cell = sheet.GetCellAt(0, i);
            cell.Value = dt.Columns[i].ColumnName;
            cell.Style.Font.Bold = true;
        }

        // Data rows
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            for (int j = 0; j < dt.Columns.Count; j++)
            {
                var value = dt.Rows[i][j];
                sheet.SetCellValue(
                    i + 1, j,
                    (value == DBNull.Value || value == null) ? "" : value
                );
            }
        }

        FileInfo fileInfo = new FileInfo(filePath);
        if (!fileInfo.Directory!.Exists)
            fileInfo.Directory.Create();

        workbook.SaveAs(filePath);
        return true;
    }
    catch (Exception ex)
    {
        Console.WriteLine("Export failed: " + ex.Message);
        return false;
    }
}

// --- Usage ---

DataTable employees = new DataTable("Employees");
employees.Columns.Add("EmployeeID", typeof(int));
employees.Columns.Add("Name", typeof(string));
employees.Columns.Add("Department", typeof(string));
employees.Rows.Add(1, "John Smith", "Engineering");
employees.Rows.Add(2, "Sarah Johnson", "Marketing");

bool success = ExportToExcel(employees, @"C:\Reports\Export.xlsx");
Console.WriteLine(success ? "Export completed." : "Export failed.");

Imports IronXL
Imports IronXL.Styles
Imports System
Imports System.Data
Imports System.IO

' --- ExcelExporter helper ---

Function ExportToExcel(dt As DataTable, filePath As String) As Boolean
    If dt Is Nothing OrElse dt.Rows.Count = 0 Then
        Return False
    End If

    Try
        Dim workbook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)
        Dim sheet As WorkSheet = workbook.CreateWorkSheet(If(dt.TableName, "Sheet1"))

        ' Bold headers in the first row
        For i As Integer = 0 To dt.Columns.Count - 1
            Dim cell = sheet.GetCellAt(0, i)
            cell.Value = dt.Columns(i).ColumnName
            cell.Style.Font.Bold = True
        Next

        ' Data rows
        For i As Integer = 0 To dt.Rows.Count - 1
            For j As Integer = 0 To dt.Columns.Count - 1
                Dim value = dt.Rows(i)(j)
                sheet.SetCellValue(i + 1, j, If(value Is DBNull.Value OrElse value Is Nothing, "", value))
            Next
        Next

        Dim fileInfo As New FileInfo(filePath)
        If Not fileInfo.Directory.Exists Then
            fileInfo.Directory.Create()
        End If

        workbook.SaveAs(filePath)
        Return True
    Catch ex As Exception
        Console.WriteLine("Export failed: " & ex.Message)
        Return False
    End Try
End Function

' --- Usage ---

Dim employees As New DataTable("Employees")
employees.Columns.Add("EmployeeID", GetType(Integer))
employees.Columns.Add("Name", GetType(String))
employees.Columns.Add("Department", GetType(String))
employees.Rows.Add(1, "John Smith", "Engineering")
employees.Rows.Add(2, "Sarah Johnson", "Marketing")

Dim success As Boolean = ExportToExcel(employees, "C:\Reports\Export.xlsx")
Console.WriteLine(If(success, "Export completed.", "Export failed."))

using IronXL;
using IronXL.Styles;
using System.Data;

DataTable dt = new DataTable("Sales");
dt.Columns.Add("Product", typeof(string));
dt.Columns.Add("Revenue", typeof(decimal));
dt.Rows.Add("Widget A", 15000.50m);
dt.Rows.Add("Widget B", 22500.75m);

WorkBook workbook = WorkBook.Create(ExcelFileFormat.XLSX);
WorkSheet sheet = workbook.CreateWorkSheet("Sales");

// Write headers with light blue background and bold font
for (int i = 0; i < dt.Columns.Count; i++)
{
    var cell = sheet.GetCellAt(0, i);
    cell.Value = dt.Columns[i].ColumnName;
    cell.Style.Font.Bold = true;
    cell.Style.SetBackgroundColor("#ADD8E6");
    cell.Style.BottomBorder.SetColor("#000000");
    cell.Style.BottomBorder.Type = BorderType.Thin;
}

// Write data rows
for (int i = 0; i < dt.Rows.Count; i++)
{
    for (int j = 0; j < dt.Columns.Count; j++)
    {
        sheet.SetCellValue(i + 1, j, dt.Rows[i][j]);
    }
}

workbook.SaveAs(@"C:\Reports\FormattedReport_IronXL.xlsx");
Console.WriteLine("Formatted Excel file created.");

Imports IronXL
Imports IronXL.Styles
Imports System.Data

Dim dt As New DataTable("Sales")
dt.Columns.Add("Product", GetType(String))
dt.Columns.Add("Revenue", GetType(Decimal))
dt.Rows.Add("Widget A", 15000.50D)
dt.Rows.Add("Widget B", 22500.75D)

Dim workbook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workbook.CreateWorkSheet("Sales")

' Write headers with light blue background and bold font
For i As Integer = 0 To dt.Columns.Count - 1
    Dim cell = sheet.GetCellAt(0, i)
    cell.Value = dt.Columns(i).ColumnName
    cell.Style.Font.Bold = True
    cell.Style.SetBackgroundColor("#ADD8E6")
    cell.Style.BottomBorder.SetColor("#000000")
    cell.Style.BottomBorder.Type = BorderType.Thin
Next

' Write data rows
For i As Integer = 0 To dt.Rows.Count - 1
    For j As Integer = 0 To dt.Columns.Count - 1
        sheet.SetCellValue(i + 1, j, dt.Rows(i)(j))
    Next
Next

workbook.SaveAs("C:\Reports\FormattedReport_IronXL.xlsx")
Console.WriteLine("Formatted Excel file created.")