时间戳与时区postgresql映射

如何将"timestamp with time zone"数据类型从postgreSql映射到System.Data.DbType我需要传递参数，因为它将转到具有"timestamp with time zone"的列

下面是我的代码:

var pOrderDate = cmdOrder.CreateParameter();
pOrderDate.ParameterName = "OrderDate";
pOrderDate.DbType = System.Data.DbType.DateTime;
pOrderDate.Value = objOrder.OrderDate;
cmdOrder.Parameters.Add(pOrderDate);

下一行导致问题:

pOrderDate.DbType = System.Data.DbType.DateTime;