如何获得一行的默认值？

Question

实际上，我正在格式化要插入到MySQL数据库中的数据，并且我正在管理NULL值。

因此，要进行管理，我在要查找数据类型的地方设置了try catch，现在必须将Catch异常的某些类型的默认值放入

。

但是我如何在VB.NET中做到这一点？

这是我的代码，对代码改进的任何建议将不胜感激

  For Each row As DataRow In ds.Tables(0).Rows
            righe = ""
            For Each column As DataColumn In ds.Tables(0).Columns
                If column.DataType = Type.GetType("System.DateTime") Then
                    Try
                        righe &= "'" & Format(row.Item(column.ColumnName), "yyyy-MM-dd") & "', "
                    Catch ex As Exception

                    End Try

                ElseIf column.DataType = Type.GetType("System.TimeSpan") Then
                    righe &= "'" & Format(row.Item(column.ColumnName).ToString, "HH\:mm\:ss") & "', "
                ElseIf column.DataType = Type.GetType("System.Int32") Then
                    righe &= row.Item(column.ColumnName) & ", "
                ElseIf column.DataType = Type.GetType("System.Single") Then
                    righe &= Replace(row.Item(column.ColumnName), ",", ".") & ", "
                ElseIf column.DataType = Type.GetType("System.Byte") Then
                    righe &= row.Item(column.ColumnName) & ", "
                ElseIf column.DataType = Type.GetType("System.Double") Then
                    righe &= Replace(row.Item(column.ColumnName), ",", ".") & ", "
                ElseIf column.DataType = Type.GetType("System.String") Then
                    righe &= "'" & APICI(row.Item(column.ColumnName)) & "', "
                End If
            Next
            righe = Mid(righe, 1, Len(righe) - 2)
        Next