主题：如何获取当月的最后一天的日期？

如果用列来表示,可以看下面代码
Dim dr As DataRow = e.DataRow
Dim y As Integer = dr("日期").Year
Dim m As Integer = dr("日期").Month
Dim Days As Integer = Date.DaysInMonth(y,m)
Dim LastDay As Date = New Date(y,m,Days)
Select Case e.DataCol.Name
    Case "日期"
        dr("最后一天日期") =LastDay
      
End Select