After create a DataGridView control that bound to a table, I still don't know how to validating the input to the DataGridView. My Datagrid :

ID_no Date Name Age Debet Credit

A001 08/06/06 Eric 25 30

A00209/06/06Daniel 23 55

A00315/08/06Catthy 26 35

I create the DataGridViewwith dragingthe data source, after Iadd connection, dataset, bindingsource and bindingnavigator with the wizard....But now when I input a invalid data, example a invalid date, or input alphabet in column Age, I want my messagebox appear to tell the user that it's a invalid data, rather than the error that displayed by system. Also....when the column debet have a value > 0,I want the user cannot input the column credit. How to make it.....???? please help me....thank's..........

Try something like this

Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim dcID As New DataGridViewTextBoxColumn With dcID .Name = "ID" .HeaderText = "ID" End With Dim dcDate As New DataGridViewTextBoxColumn With dcDate .Name = "Date" .HeaderText = "Date" End With Dim dcCredit As New DataGridViewTextBoxColumn With dcCredit .Name = "Credit" .HeaderText = "Credit" End With Dim dcDebit As New DataGridViewTextBoxColumn With dcDebit .Name = "Debit" .HeaderText = "Debit" End With DataGridView1.Columns.Add(dcID) DataGridView1.Columns.Add(dcDate) DataGridView1.Columns.Add(dcDebit) DataGridView1.Columns.Add(dcCredit) End Sub Private Sub DataGridView1_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles DataGridView1.CellValidating Dim strName As String = DataGridView1.Columns(e.ColumnIndex).Name If String.IsNullOrEmpty(e.FormattedValue.ToString) Then Return Select Case strName Case "Date" Dim dt As Date If Not DateTime.TryParse(e.FormattedValue.ToString, dt) Then MessageBox.Show("Invalid Date") e.Cancel = True End If Case "Debit" Dim dDebit As Decimal Dim bValid As Boolean = Decimal.TryParse(e.FormattedValue.ToString, dDebit) Dim strCredit As String strCredit = DataGridView1.Item("Credit", e.RowIndex).FormattedValue.ToString If String.IsNullOrEmpty(e.FormattedValue.ToString) Then Return If bValid And strCredit.Length < 1 Then ' everything is good Else MessageBox.Show("Invalid number or credit not empty") e.Cancel = True End If Case "Credit" Dim dCredit As Decimal Dim bValid As Boolean = Decimal.TryParse(e.FormattedValue.ToString, dCredit) Dim strDebit As String = DataGridView1.Item("Debit", e.RowIndex).FormattedValue.ToString If bValid And strDebit.Length < 1 Then ' everything is good Else MessageBox.Show("Invalid number or debit not empty") e.Cancel = True End If End Select End Sub End Class

Try something like this

Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim dcID As New DataGridViewTextBoxColumn With dcID .Name = "ID" .HeaderText = "ID" End With Dim dcDate As New DataGridViewTextBoxColumn With dcDate .Name = "Date" .HeaderText = "Date" End With Dim dcCredit As New DataGridViewTextBoxColumn With dcCredit .Name = "Credit" .HeaderText = "Credit" End With Dim dcDebit As New DataGridViewTextBoxColumn With dcDebit .Name = "Debit" .HeaderText = "Debit" End With DataGridView1.Columns.Add(dcID) DataGridView1.Columns.Add(dcDate) DataGridView1.Columns.Add(dcDebit) DataGridView1.Columns.Add(dcCredit) End Sub Private Sub DataGridView1_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles DataGridView1.CellValidating Dim strName As String = DataGridView1.Columns(e.ColumnIndex).Name If String.IsNullOrEmpty(e.FormattedValue.ToString) Then Return Select Case strName Case "Date" Dim dt As Date If Not DateTime.TryParse(e.FormattedValue.ToString, dt) Then MessageBox.Show("Invalid Date") e.Cancel = True End If Case "Debit" Dim dDebit As Decimal Dim bValid As Boolean = Decimal.TryParse(e.FormattedValue.ToString, dDebit) Dim strCredit As String strCredit = DataGridView1.Item("Credit", e.RowIndex).FormattedValue.ToString If String.IsNullOrEmpty(e.FormattedValue.ToString) Then Return If bValid And strCredit.Length < 1 Then ' everything is good Else MessageBox.Show("Invalid number or credit not empty") e.Cancel = True End If Case "Credit" Dim dCredit As Decimal Dim bValid As Boolean = Decimal.TryParse(e.FormattedValue.ToString, dCredit) Dim strDebit As String = DataGridView1.Item("Debit", e.RowIndex).FormattedValue.ToString If bValid And strDebit.Length < 1 Then ' everything is good Else MessageBox.Show("Invalid number or debit not empty") e.Cancel = True End If End Select End Sub End Class

Thank you Kent.... It's really solve my problem......