Question

C#同一张表中对字段1的值依次进行运算后将结果对应写入字段2

现有日期字段time和字符字段day，我想利用当前时间减去time中的日期获取中间的天数差值，百思不得其解，求大神给段代码。小的错误代码附上：
public void getdays() { WindowsFormsApplication1.DataBase sqlhelper = new WindowsFormsApplication1.DataBase(); DataSet dt = new DataSet(); sql1 = "SELECT * FROM dhqgsj WHERE Nu_time = " + pid; dt = sqlhelper.ExecuteDataSet(sql); if (dt.Tables[0].Rows.Count > 0) { DateTime dt2 = System.DateTime.Now; TimeSpan ts = dt2 - dt1; a = ts.Days; sql = "update dhqgsj set Nu_day = '" + a.ToString() + "' where id= " + pid; dt = sqlhelper.ExecuteDataSet(sql); } }

Answer 1

select datediff(day,数据库时间字段,getdate()) from Users --两日期间隔天