每当我更新gridview时，如何将今天的日期更新到数据库

I have this table called EVENT_ANNOUNCE. After clicking edit button on the gridview, and once clicking the update button, I would like to update today date to the column field MODIFIEDDATE in the database. If clicked cancel, it will not update today date to the column field MODIFIEDDATE. I only want update.I have this table called EVENT_ANNOUNCE. After