VB.NET: Clear DataGridView

问题:

I've tried -

DataGridView1.DataSource=Nothing

and

DataGridView1.DataSource=Nothing
DataGridView1.Refresh()

and

DataGridView1.RefreshEdit()

None of them works..

I've written a method that sets the DataSource of the DataGridView when executed. but each time i execute it, it replicates the data with new value and appends it to the previous contents of the DGV.. I wanna clear the content and then add the values.. Is that possible?

回答1:

If the DataGridView is bound to any datasource, you'll have to set the DataGridView's DataSource property to Nothing.

If the DataGridView is not bound to any data source, this code will do the trick:

DataGridView.Rows.Clear()

回答2:

For unbound cases note that:

DataGridView.Rows.Clear()

leaves the Columns collection in place.

DataGridView.Columns.Clear()

..will remove all the columns and rows. If you are using the DGV unbound, and on next use the columns change, clearing the Rows may not be adequate. For library code clear all the columns before adding columns.

回答3:

I'd probably use this...

DataGridView1.Rows.Clear()

to clear out the rows and then rebind.

回答4:

Follow the easy way like this

assume that ta is a DataTable

ta.clear()
DataGridView1.DataSource = ta
DataGridView1.DataSource = Nothing

回答5:

Can you not bind the datagridview to an empty collection (instead of null). That do the trick?

回答6:

To remove the old record in datagridview when you are searching for new result,with button_click event write the following code,

me.DataGridview1.DataSource.clear()

this code will help to remove the old record in datagridview.

回答7:

I found that setting the datasource to null removes the columns. This is what works for me:

c#:

((DataTable)myDataGrid.DataSource).Rows.Clear();

VB:

Call CType(myDataGrid.DataSource, DataTable).Rows.Clear()

回答8:

My DataGridView is also bound to a DataSource and myDataGridView.Columns.Clear() worked fine but myDataGridView.Rows.Clear() did NOT. Just an FYI for those who have tried .Rows.

回答9:

Don't do anything on DataGridView, just clear the data source. I tried clearing myDataset.clear() method, then it worked.

回答10:

I've got this code working in a windows form,

Public Class Form1

    Private dataStuff As List(Of String)


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        DataGridView1.DataSource = Nothing

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        dataStuff = New List(Of String)

        dataStuff.Add("qwerty")
        dataStuff.Add("another")
        dataStuff.Add("...and another")

        DataGridView1.DataSource = dataStuff
    End Sub
End Class

回答11:

You should remove the table from dataset if the datagrid is bind to some datatable. Your Gridview will be cleared automatically. No other way.

[YourDatasetName].Tables.Clear()

回答12:

I had the same problem on gridview content clearing. The datasource i used was a datatable having no columns, and i added columns and rows programmatically to datatable. Then bind to datagridview. I tried the code related with gridview like gridView.Rows.Clear(), gridView.DataSource = Nothing

but it didn't work for me. Then try the below code related with datatable before binding it to datagridview each time.

  dtStore.Rows.Clear()
  dtStore.Columns.Clear()
  gridView.DataSource = dtStore

And is working fine, no replication in DataGridView

回答13:

1) create button named it Clear.Inside insert tfhe following code datagridviewer.DataSource=nothing

2) In your search button begin your code by the following statement

datagridviewer.DataSource = DataSet.table

Nb:instead of table put the real name of your table ex: datagridviewer.DataSource = DataSet.client

回答14:

When feeding info from an SQL query into a datagridview you can clear the datagridview first before reloading it.

Where I have defined dbDataSet as New DataTable I can do a clear. dbDataSet must be at the start of the form within the Public Class Form

Dim dbDataset AS New DataTable

within the code of you Private Sub, place

dbDataSet.Clear()

回答15:

You may have a user scenario such that you want to keep the data binding and only temporarily clear the DataGridView. For instance, you have the user click on a facility on a map to show its attributes for editing. He is clicking for the first time, or he has already clicked on one and edited it. When the user clicks the "Select Facility" button, you would like to clear the DataGridView of the data from the previous facility (and not throw an error if it's his first selection). In this scenario, you can achieve the clean DataGridView by adapting the generated code that fills the DataGridView. Suppose the generated code looks like this:

    Try
        Me.Fh_maintTableAdapter.FillByHydrantNumber(Me.Fh2010DataSet.fh_maint, hydrantNum)
    Catch ex As System.Exception
        System.Windows.Forms.MessageBox.Show(ex.Message)
    End Try

We are filling the DataGridView based on the hydrant number. Copy this code to the point where you want to clear the DataGridView and substitute a value for "hydrantNum" that you know will retrieve no data. The grid will clear. And when the user actually selects a facility (in this case, a hydrant), the binding is in place to fill the DataGridView appropriately.

回答16:

If the DataGridView is bound to any datasource,

DataGridView1.DataSource = Nothing
DataGridView1.DataBind()

回答17:

Dim DS As New DataSet

DS.Clear() - DATASET clear works better than DataGridView.Rows.Clear() for me :

Public Sub doQuery(sql As String)
   Try
        DS.Clear()  '<-- here
        '   - CONNECT -
        DBCon.Open()
        '   Cmd gets SQL Query
        Cmd = New OleDbCommand(sql, DBCon)
        DA = New OleDbDataAdapter(Cmd)
        DA.Fill(DS)
        '   - DISCONNECT -
        DBCon.Close()
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

回答18:

If the GridView (Say the name is gvArchive) is bound to any DataSource, the following will clear it:

gvArchive.DataSource = Nothing

gvArchive.DataBind()

回答19:

just write this

DataGridView1.DataSource = ""

回答20:

I had the same problem: I was programmatically binding my GridView1 to one SQL table [dictonary] or another [meny] BUT when I selected the second table from my RadioButtonList1, I was getting an error (System.Web.HttpException: Field or property with the title [the first column's title from the previously selected table] was not found in the selected data source.) i.e. saying that the columns from my first-selected table couldn't be found. All I needed to do was insert:

GridView1.Columns.Clear()

before adding the table columns. Here goes the full code:

Dim connectionString As String = "your-string-details"
Dim connection As New SqlConnection(connectionString)

Then comes your first Sub:

Private Sub BindOrders()
    connection.Open()

    Dim sqlCommand As String = "SELECT * FROM [dictionary]" 
    Dim dataAdapter As New SqlDataAdapter(sqlCommand, connection)
    Dim dt As New DataTable() 
    dataAdapter.Fill(dt)

    GridView1.Columns.Clear() ' clear columns before adding new ones

    If GridView1.Columns.Count <= 0 Then
        Dim Field As New BoundField()
        Field.DataField = "id"
        Field.HeaderText = "id"
        GridView1.Columns.Add(Field)

        Field = New BoundField()
        Field.DataField = "strArHundreds"
        Field.HeaderText = "strArHundreds"
        GridView1.Columns.Add(Field)

        Field = New BoundField()
        Field.DataField = "strArTens"
        Field.HeaderText = "strArTens"
        GridView1.Columns.Add(Field)

        Field = New BoundField()
        Field.DataField = "strArSingles"
        Field.HeaderText = "strArSingles"
        GridView1.Columns.Add(Field)
    End If

    GridView1.DataSource = dt
    GridView1.DataBind()

    connection.Close()
End Sub

Then comes your second Sub:

Private Sub BindDocuments()
    connection.Open()

    Dim sqlCommand As String = "SELECT * FROM [meny]"
    Dim dataAdapter As New SqlDataAdapter(sqlCommand, connection)
    Dim dt As New DataTable()

    dataAdapter.Fill(dt)

    GridView1.Columns.Clear() ' clear columns before adding new ones

    If GridView1.Columns.Count <= 0 Then
        Dim Field As New BoundField
        Field = New BoundField
        Field.DataField = "id"
        Field.HeaderText = "id"
        GridView1.Columns.Add(Field)

        Field = New BoundField
        Field.DataField = "nazev"
        Field.HeaderText = "nazev"
        GridView1.Columns.Add(Field)
    End If

    GridView1.DataSource = dt
    GridView1.DataBind()

    connection.Close()
End Sub

Finally comes your RadioButton:

Protected Sub RadioButtonList1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles RadioButtonList1.SelectedIndexChanged
    Dim index As Integer
    index = RadioButtonList1.SelectedIndex
    Select Case index
        Case 0
            BindOrders()
            Exit Select
        Case 1
            BindDocuments()
            Exit Select
    End Select
End Sub

For completion, here is the code for the GridView1 and the RadioButtonList1 in the associated aspx.file:

<asp:RadioButtonList ID="RadioButtonList1"
    runat="server"
    AutoPostBack="True"
    OnSelectedIndexChanged="RadioButtonList1_SelectedIndexChanged">
    <asp:ListItem>Obraty</asp:ListItem>
    <asp:ListItem>Dokumenty</asp:ListItem>
</asp:RadioButtonList>

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
</asp:GridView>

This all works well now.

回答21:

The mistake that you are making is that you seem to be using a dataset object for storing your data. Each time you use the following code to put data into your dataset you add data to the data already in your dataset.

myDataAdapter.Fill(myDataSet)

If you assign the table in your dataset to a DataGridView object in your program by the following code you will get duplicate results because you have not cleared data which is already residing in your dataset and in your dataset table.

myDataGridView.DataSource = myDataSet.Tables(0)

To avoid replicating the data you have to call clear method on your dataset object.

myDataSet.clear()

An then assign the table in your dataset to your DataGridView object. The code is like this.

myDataSet.clear()
myDataAdapter.Fill(myDataSet)
myDataGridView.DataSource = myDataSet.Tables(0)

You can try this code:

' clear previous data
DataGridView2.DataSource = Nothing
DataGridView2.DataMember = Nothing
DataGridView2.Refresh()
Try
    connection.Open()
    adapter1 = New SqlDataAdapter(sql, connection)
    ' clear data already in the dataset
    ds1.Clear()
    adapter1.Fill(ds1)
    DataGridView2.DataSource = ds1.Tables(0)
    connection.Close()
Catch ex As Exception
    MsgBox(ex.ToString)
End Try

回答22:

You can do in this way:

DataGridView1.Enable = false
DataGridView1.DataSource = Nothing
DataGridView1.Enable = true

回答23:

For the Clear of Grid View Data You Have to clear the dataset or Datatable

I use this Code I clear the Grid View Data even if re submit again and again it will work Example Dim con As New OleDbConnection Dim cmd As New OleDbCommand Dim da As New OleDbDataAdapter Dim dar As OleDbDataReader Dim dt As New DataTable If (con.State <> 1) Then con.Open() End If dt.Clear() 'To clear Data Every time to fresh data cmd.Connection = con cmd.CommandText = "select * from users" da.SelectCommand = cmd da.Fill(dt) DataGridView1.DataSource = dt DataGridView1.Visible = True

    cmd.Dispose()
    con.Close()

回答24:

You can do that only by the following 2 lines:

DataGridView1.DataSource=Nothing
DataGridView1.DataBind()

回答25:

You can also try this code if you want to clear all data in your DataGridView

DataGridView1.DataSource.Clear()