问题描述
我正在尝试使用 VB 将数据表导入 Excel。我找到了很多方法来做到这一点,但所有方法都给我带来了问题。
我尝试的第一种方法是使用 ClosedXML。它非常适合导入数据,但它弄乱了数据透视表。这是一个已知的问题。另外,如果数据表太大,它会抛出内存不足异常,这是另一个已知问题。
然后我切换到 Interop。但是使用 Interop 我只能找到一种导入数据的方法,那就是双循环,如下所示。对我来说,这里的问题是,导入一个 3k 行、39 列的表需要超过 15 分钟。无论如何,这种方法对我来说似乎很慢且效率低下,而且我无法想象 Microsoft 没有实施一种更有效的方法来导入更大的数据表。
有人可以告诉我更好的方法吗?
For i As Integer = 0 To datatable.Rows.Count() - 1
For j As Integer = 0 To datatable.Columns.Count() - 1
xlWorkSheet.Cells(i + 2,j + 1) = datatable.Rows(i)(j).ToString()
Next
Next
'dt is your Datatable and xlWorksheet is Your Worksheet
Dim cc = dt.Columns.Count
Dim rc = dt.Rows.Count
Dim arr(rc - 1,cc - 1) As Object
For r = 0 To rc - 1
Dim dr = dt.Rows(r)
For c = 0 To cc - 1
arr(r,c) = dr(c).ToString 'I added ToString() here,because it raised an type error
Next
Next
xlWorkSheet.Range("A2").Resize(rc,cc).Value = arr
解决方法
逐个单元格填充 Excel 范围很慢,您可以创建二维数组并从数据表填充它,然后将此数组分配给 Excel 范围。
在我对具有 3000 行和 39 列的数据表进行的测试中,此代码需要 670 毫秒。
'dt is your Datatable and xlWorksheet is Your Worksheet
Dim cc = dt.Columns.Count
Dim rc = dt.Rows.Count
Dim arr(rc - 1,cc - 1) As Object
For r = 0 To rc - 1
Dim dr = dt.Rows(r)
For c = 0 To cc - 1
arr(r,c) = dr(c)
Next
Next
xlWorkSheet.Range("A2").Resize(rc,cc).Value = arr
测试:
Private Sub Button1_Click(sender As Object,e As EventArgs) Handles Button1.Click
Dim xl = New Excel.Application
Dim wb = xl.Workbooks.Add()
Dim xlWorkSheet As Excel.Worksheet = CType(wb.Worksheets(1),Excel.Worksheet)
Dim dt = CreateDatatable()
Dim cc = dt.Columns.Count
Dim rc = dt.Rows.Count
Dim tt = Now.Ticks
Dim arr(rc - 1,cc).Value = arr
Dim ee = (Now.Ticks - tt) / 10000
MsgBox(ee)
xl.Visible = True
xl.UserControl = True
End Sub
Function CreateDatatable() As DataTable
Dim dt = New DataTable
For c = 1 To 39
dt.Columns.Add($"Col{c}")
Next
For r = 1 To 3000
Dim dr As DataRow = dt.NewRow
For c = 1 To 39
dr(c - 1) = $"R{r},C{c}"
Next
dt.Rows.Add(dr)
Next
Return dt
End Function