vb2008

--Button控件代码
--数据查询
--单变量
Try
  Me.TMPTableAdapter.cs2(Me.DataSet1.TMP, CType(GOODSIDToolStripTextBox.Text, Decimal))
Catch ex As System.Exception
  System.Windows.Forms.MessageBox.Show(ex.Message)
End Try
--双变量
Try
  Me.TMPTableAdapter.cs4(Me.DataSet1.TMP, CType(GoodsidToolStripTextBox2.Text, Decimal), GoodscodeToolStripTextBox1.Text)
Catch ex As System.Exception
  System.Windows.Forms.MessageBox.Show(ex.Message)
End Try
--三变量
Try
  Me.TMPTableAdapter.cs3(Me.DataSet1.TMP, CType(GoodsidToolStripTextBox1.Text, Decimal), GOODSCODEToolStripTextBox.Text, BRANDNAMEToolStripTextBox.Text)
Catch ex As System.Exception
  System.Windows.Forms.MessageBox.Show(ex.Message)
End Try
--变量判断
Try
    If (GOODSCODEToolStripTextBox.Text.Trim() = "") And (BRANDNAMEToolStripTextBox.Text.Trim() = "") Then
        Me.TMPTableAdapter.cs2(Me.DataSet1.TMP, CType(GoodsidToolStripTextBox1.Text, Decimal))
    ElseIf (BRANDNAMEToolStripTextBox.Text.Trim() = "") Then
        Me.TMPTableAdapter.cs4(Me.DataSet1.TMP, CType(GoodsidToolStripTextBox1.Text, Decimal), GOODSCODEToolStripTextBox.Text)
    Else
        Me.TMPTableAdapter.cs3(Me.DataSet1.TMP, CType(GoodsidToolStripTextBox1.Text, Decimal), GOODSCODEToolStripTextBox.Text, BRANDNAMEToolStripTextBox.Text)
    End If
Catch ex As System.Exception
    System.Windows.Forms.MessageBox.Show(ex.Message)
End Try
--窗体调用
Form2.Show()
Me.Hide()
判断TextBox的内容为空:
if(textbox1.text.trim()= " "){
        //do   something
}
else{
      //do   else
}
....
判断一个textbox对象是否为空
if(textbox1==null)
//do   something

这个问题在百度的时候可以得到很多答案，而且还有些答案会有将导出的excel表保存到某个地方的代码。
毕竟某些知识点不是永远都要死记住的。

因为你要用到excel表，所以要首先在项目里添加引用哟：
项目（project）-添加引用（add reference）-Microsoft .Office.Interop.Excel

在form1窗体里
添加一个dataGridView1
dataGridView的属性里有一个allowUsersToAddRows，要设置成FALSE
再添加一个Button1


Button1内的代码：

'要先添加引用才能用到 Microsoft.Office.Interop.Excel.Application()
Dim MyExcel As New Microsoft.Office.Interop.Excel.Application()
MyExcel.Application.Workbooks.Add(True)
MyExcel.Visible = True
'去除dataGridView1的编号列（这里也可以不要）
Dim m As Integer
For m = 0 To DataGridView1.ColumnCount - 1
MyExcel.Cells(1, m + 1) = Me.DataGridView1.Columns(m).HeaderText
Next m
'往excel表里添加数据
Dim i As Integer
For i = 0 To DataGridView1.RowCount - 1
Dim j As Integer
For j = 0 To DataGridView1.ColumnCount - 1
If Me.DataGridView1(j, i).Value Is System.DBNull.Value Then
MyExcel.Cells(i + 2, j + 1) = ""
Else
MyExcel.Cells(i + 2, j + 1) = DataGridView1(j, i).Value.ToString
End If
Next j
Next i

对于dataGridView怎样获得数据库里的数据。
这里就不写了。既然用到了导出数据，相信你一定早就会把数据库里的数据导出到dataGridView里了。

----导入excel2

        ' Create the Excel Application object
        Dim excelApp As New ApplicationClass()
        ' Create a new Excel Workbook
        Dim excelWorkbook As Workbook = excelApp.Workbooks.Add(Type.Missing)
        Dim sheetIndex As Integer = 0
        Dim col, row As Integer
        Dim excelSheet As Worksheet
        ' Copy each DataTable as a new Sheet
        For Each dt As System.Data.DataTable In DataSet.Tables
            sheetIndex += 1
            ' Copy the DataTable to an object array
            Dim rawData(dt.Rows.Count, dt.Columns.Count - 1) As Object
            ' Copy the column names to the first row of the object array
            For col = 0 To dt.Columns.Count - 1
                rawData(0, col) = dt.Columns(col).ColumnName
            Next
            ' Copy the values to the object array
            For col = 0 To dt.Columns.Count - 1
                For row = 0 To dt.Rows.Count - 1
                    rawData(row + 1, col) = dt.Rows(row).ItemArray(col)
                Next
            Next
            ' Calculate the final column letter
            Dim finalColLetter As String = String.Empty
            Dim colCharset As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            Dim colCharsetLen As Integer = colCharset.Length
            If dt.Columns.Count > colCharsetLen Then
                finalColLetter = colCharset.Substring( _
                 (dt.Columns.Count - 1) \ colCharsetLen - 1, 1)
            End If
            finalColLetter += colCharset.Substring( _
              (dt.Columns.Count - 1) Mod colCharsetLen, 1)
            ' Create a new Sheet
            excelSheet = CType( _
                excelWorkbook.Sheets.Add(excelWorkbook.Sheets(sheetIndex), _
                Type.Missing, 1, XlSheetType.xlWorksheet), Worksheet)
            excelSheet.Name = dt.TableName
            ' Fast data export to Excel
            Dim excelRange As String = String.Format("A1:{0}{1}", finalColLetter, dt.Rows.Count + 1)
            excelSheet.Range(excelRange, Type.Missing).Value2 = rawData
            ' Mark the first row as BOLD
            CType(excelSheet.Rows(1, Type.Missing), Range).Font.Bold = True
            excelSheet = Nothing
        Next
        ' Save and Close the Workbook
        excelWorkbook.SaveAs("D:\aaa.xls", XlFileFormat.xlWorkbookNormal, Type.Missing, _
         Type.Missing, Type.Missing, Type.Missing, XlSaveAsAccessMode.xlExclusive, _
         Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing)
        excelWorkbook.Close(True, Type.Missing, Type.Missing)
        excelWorkbook = Nothing
        ' Release the Application object
        excelApp.Quit()
        excelApp = Nothing
        ' Collect the unreferenced objects
        GC.Collect()
        GC.WaitForPendingFinalizers()

' 返回当前时间
Function GetTime() As String
  Return CStr(Now)
End Function

'引用函数
MsgBox(GetTime)

Dim i As Integer = 0
For i = 1 To 10
  DisplayNumber(i)
Next

If My.Computer.Clock.LocalTime.DayOfWeek = DayOfWeek.Monday Then
  MsgBox("Today is Monday!")
End If

Dim number, digits As Integer
Dim myString As String
number = 53
If number < 10 Then
    digits = 1
ElseIf number < 100 Then
    digits = 2
Else
    digits = 3
End If
If digits = 1 Then myString = "One" Else myString = "More than one"

Dim number As Integer = 8
Select Case number
    Case 1 To 5
        Debug.WriteLine("Between 1 and 5, inclusive")
        ' The following is the only Case clause that evaluates to True.
    Case 6, 7, 8
        Debug.WriteLine("Between 6 and 8, inclusive")
    Case 9 To 10
        Debug.WriteLine("Equal to 9 or 10")
    Case Else
        Debug.WriteLine("Not between 1 and 10, inclusive")
End Select

在代码中可以使用 Try...Catch...Finally 块来处理运行时错误。您可以 Try 一段代码，如果这段代码发出异常，它将跳转到 Catch 块，然后执行 Catch 块中的代码。以上代码执行完后，执行 Finally 块中的所有代码。整个 Try...Catch...Finally 块由 End Try 语句结束。

下面的示例阐释了如何使用每一个块。

Try
  ' Code here attempts to do something.
Catch
  ' If an error occurs, code here will run.
Finally
  ' Code in this block will always run.
End Try


        Try
            Dim aNumber As Double = CDbl(TextBox1.Text)
            MsgBox("You entered the number " & aNumber)
        Catch
            MsgBox("Please enter a number.")
        Finally
            MsgBox("Why not try it again?")
        End Try

DateTimePicker1控件，主窗口赋值
Me.DateTimePicker1.Text = System.DateTime.Now

--日期返回
    'TextBox1.Text = Convert.ToString(Format("yyyyMMdd", DateTimePicker1.Value))
        Dim tmp0 As String
        If DateTimePicker1.Value.Day < 10 Then
            tmp0 = (0 & DateTimePicker1.Value.Day)
        Else
            tmp0 = DateTimePicker1.Value.Day
        End If
        TextBox1.Text = Year(DateTimePicker1.Value) & Month(DateTimePicker1.Value) & tmp0

if(textbox1.text.trim()= " "){
        //do   something
}
else{
      //do   else
}
....
判断一个textbox对象是否为空
if(textbox1==null)
//do   something

--下拉框
        Dim tmp1 As String = ComboBox1.Text
        If tmp1 = 1 Then
            TextBox1.Text = "购销"
        Else
            TextBox1.Text = "代销"
        End If