【VB.NET】DataTableのデータをCSVに出力する方法

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        '1, 2列目のみ抽出（重複排除なし）
        dt = dt.DefaultView.ToTable(False, "Col1", "Col2")

        Dim sb As New StringBuilder

        Using sr As New System.IO.StreamWriter("output.csv", False, Encoding.GetEncoding("utf-8"))
            'ヘッダ編集
            For Each col As DataColumn In dt.Columns
                If sb.Length > 0 Then
                    sb.Append(",")
                End If
                sb.Append("""").Append(col.ColumnName).Append("""")
            Next

            'データ編集
            For Each row As DataRow In dt.Rows
                sb.AppendLine()
                sb.Append(String.Join(",",
                                      row.ItemArray.Select(
                                      Function(data) """" & data & """")))
            Next

            'CSV出力
            sr.Write(sb.ToString)
        End Using

    End Sub

    Dim dt As New DataTable
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        With dt
            .Columns.Add("Col1")
            .Columns.Add("Col2")
            .Columns.Add("Col3")
            .Rows.Add("A001", "B001", "C001")
            .Rows.Add("A002", "B002", "C002")
            .Rows.Add("A003", "B003", "C003")
            .Rows.Add("A004", "B004", "C004")
            .Rows.Add("A005", "B005", "C005")
        End With

        'DGV設定
        With DataGridView1
            .DataSource = dt
            .AllowUserToAddRows = False
            .ClearSelection()
        End With

    End Sub