用它来表示金额。可这种类型非常精确，当你在数据库里插入一条数据是6.00时，在显示时却是6.000000000000000000000。在页面显示非常不美观。它不仅可以做到double和float，而且在商业计算上也能显示它的作用。-Use it to that amount. This type can be very precise, when you insert a data in the database is 6.00 pm at the display Shique is 6.000000000000000000000. The page displays a very unsightly. It not only can do double and float, but also in business computing and its role can be displayed.