How Can Datagridview CheckBox unChecked

Question

I added a checkbox and a new column to the datagridview. The checkbox is being checked automatically when adding data to this column. If we delete this data thinking it is not necessary
The checkbox is still checked. I mean, once I give the data, the checkbox must be checked, but if I remove this data, how to unchecked the automatic checkbox
Goes.
I am making this effort on VB.net.
Thanks in advance to the experienced collaborators.

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim checkboxcolumn As New DataGridViewCheckBoxColumn()
checkboxcolumn.HeaderText = "*"
checkboxcolumn.Width = 20
checkboxcolumn.Name = "checkboxcolomn"
DataGridView1.Columns.Insert(0, checkboxcolumn)
End Sub

Sub display_data()
Dim cmd As New SqlCommand("select * from tbl_Pro", con)
Dim da As New SqlDataAdapter(cmd)
Dim dt As New DataTable
dt.Clear()
da.Fill(dt)
DataGridView1.DataSource = dt
dt.Columns.Add("Qty")
End Sub

Private Sub DataGridView1_CellValueChanged(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellValueChanged
Dim cell1 As DataGridViewCheckBoxCell = DataGridView1.Rows(e.RowIndex).Cells(0)
cell1.Value = True
End Sub

Answer 1

Hi @jewel ,
You can set the value of the checkboxcolomn column by determining whether the NewColumn data of the current row is empty in DataGridView1.CellValueChanged.

Private Sub DataGridView1_CellValueChanged(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellValueChanged  
    If DataGridView1("NewColumn", e.RowIndex).Value.ToString.Equals("") Then  
        DataGridView1("checkboxcolomn", e.RowIndex).Value = False  
    Else  
        DataGridView1("checkboxcolomn", e.RowIndex).Value = True  
    End If  
End Sub  

Hope the code above could be helpful.
Best Regards.
Jiachen Li

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Answer 2

Hi
Difficult to understand what you are asking for. I think you need to have the checkbox auto check / uncheck depending on some other column - moybe!
Anyway, here is some code that may help. This example explicitly loads the datatable but yours takes from a database - the ideas are the same.
What I do here: set up the datatable with some columns, add some random data just for the example. Then, run through a loop to set the additional boolean column values according to the rules I have used (column [Two] empty = False, column [Two] not empty = True)

After that, changing the value of a cell in column [Two] will auto check / uncheck the first (checkboxcolomn) column.

Option Strict On
Option Explicit On
Public Class Form1
    Dim dt As New DataTable("Freddy")
    Dim r As New Random
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        With dt
            .Columns.Add("One", GetType(Integer))
            .Columns.Add("Two", GetType(String))
            .Columns.Add("Three", GetType(Double))

            For i As Integer = 0 To 99
                .Rows.Add(r.Next(9, 99), IIf(r.Next(0, 2) = 1, "Freddy", String.Empty), r.NextDouble() * 99)
            Next
        End With
        DataGridView1.DataSource = dt


        Dim checkboxcolumn As New DataGridViewCheckBoxColumn()
        With checkboxcolumn
            .HeaderText = "*"
            .Width = 20
            .Name = "checkboxcolomn"
        End With
        DataGridView1.Columns.Insert(0, checkboxcolumn)

        For index As Integer = 0 To DataGridView1.Rows.Count - 1
            If Not index = DataGridView1.NewRowIndex Then
                DataGridView1("checkboxcolomn", index).Value = Not DataGridView1("Two", index).Value.ToString = String.Empty
            End If
        Next
    End Sub
    Private Sub DataGridView1_CellValueChanged(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellValueChanged
        DataGridView1("checkboxcolomn", e.RowIndex).Value = Not DataGridView1("Two", e.RowIndex).Value.ToString = String.Empty
    End Sub
End Class