this is for numeric (decimal) arguments.. use for bills.vb ...create an event handler for the ColumnChanging event that ensures that the UnitPrice, UnitsInStock, UnitsOnOrder, and ReorderLevel column values (if not NULL) are greater than or equal to zero. If any such column is out of range, throw an ArgumentException.
ProductsDataTable.ColumnChanging.vb
Public Class BlogCategorysDataTable
Imports System.data
Partial Public Class Northwind
Partial Public Class ProductsDataTable
Public Overrides Sub BeginInit()
AddHandler Me.ColumnChanging, AddressOf ValidateColumn
End Sub
Sub ValidateColumn(ByVal sender As Object, ByVal e As DataColumnChangeEventArgs)
If e.Column.Equals(Me.UnitPriceColumn) Then
If Not Convert.IsDBNull(e.ProposedValue) AndAlso _
CType(e.ProposedValue, Decimal) < 0 Then
Throw New ArgumentException( _
"UnitPrice cannot be less than zero", "UnitPrice")
End If
ElseIf e.Column.Equals(Me.UnitsInStockColumn) OrElse _
e.Column.Equals(Me.UnitsOnOrderColumn) OrElse _
e.Column.Equals(Me.ReorderLevelColumn) Then
If Not Convert.IsDBNull(e.ProposedValue) AndAlso _
CType(e.ProposedValue, Short) < 0 Then
Throw New ArgumentException(String.Format( _
"{0} cannot be less than zero", e.Column.ColumnName), _
e.Column.ColumnName)
End If
End If
End Sub
End Class
End Class