本文整理汇总了VB.NET中System.Data.ConstraintCollection.CollectionChanged事件的典型用法代码示例。如果您正苦于以下问题：VB.NET ConstraintCollection.CollectionChanged事件的具体用法？VB.NET ConstraintCollection.CollectionChanged怎么用？VB.NET ConstraintCollection.CollectionChanged使用的例子？那么恭喜您, 这里精选的事件代码示例或许可以为您提供帮助。您也可以进一步了解该事件所在类System.Data.ConstraintCollection的用法示例。
在下文中一共展示了ConstraintCollection.CollectionChanged事件的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的VB.NET代码示例。
示例1: ConstraintCollectionChanged
Private Shared Sub ConstraintCollectionChanged()
' Demonstrate ConstraintCollection.CollectionChanged event.
Try
' Create Customers table.
Dim customersTable As New DataTable("Customers")
customersTable.Columns.Add("id", Type.GetType("System.Int32"))
customersTable.Columns.Add("Name", Type.GetType("System.String"))
AddHandler customersTable.Constraints.CollectionChanged, _
New System.ComponentModel.CollectionChangeEventHandler( _
AddressOf Collection_Changed)
' Create Orders table.
Dim ordersTable As New DataTable("Orders")
ordersTable.Columns.Add("CustID", Type.GetType("System.Int32"))
ordersTable.Columns.Add("CustName", Type.GetType("System.String"))
AddHandler ordersTable.Constraints.CollectionChanged, _
New System.ComponentModel.CollectionChangeEventHandler( _
AddressOf Collection_Changed)
' Create unique constraint.
Dim constraint As New UniqueConstraint(customersTable.Columns("id"))
customersTable.Constraints.Add(constraint)
' Create unique constraint and specify as primary key.
ordersTable.Constraints.Add( _
"pKey", ordersTable.Columns("CustID"), True)
' Remove constraints.
customersTable.Constraints.RemoveAt(0)
' Results in an Exception. You can't remove
' a primary key constraint.
ordersTable.Constraints.RemoveAt(0)
Catch ex As Exception
' Process exception and return.
Console.WriteLine($"Exception of type {ex.GetType()} occurred.")
End Try
End Sub
Private Shared Sub Collection_Changed(sender As object, _
ex As System.ComponentModel.CollectionChangeEventArgs)
Console.WriteLine($"List_Changed Event: '{ex.Action}'{vbTab} element={ex.Element}")
End Sub