无法将列'EffectiveDate'设置为null。请改用DBNull。 [英] Cannot set Column 'EffectiveDate' to be null. Please use DBNull instead.

问题描述

我收到错误无法将列'EffectiveDate'设置为null。请改用DBNull。

我的代码是

 dt.Columns.Add（  EffectiveDate， typeof （DateTime））; 
 
 DateTime？ effectivedate =  null ; 
 
 
  if （lastRow [  Effective_x0020_Date]！= DBNull.Value）
 {
 
 effectivedate = Convert.ToDateTime（lastRow [   Effective_x0020_Date]）; 
} 
 
 
 DataRow dr = dt.NewRow（）; 
 dr [  EffectiveDate] = effectivedate; 
 dt.Rows.Add（dr）; 
 

i跟随很多东西



http://codeverge.com/asp.net.presentation-controls/how- to-return-dbnull.value-inst / 487162 [ ^ ]



但同样的错误我正在获取

解决方案

只是因为lastRow [Effective_x0020_Date]是DBNull吗？那么你将在effectivedate中得到初始值（null）;



在分配数据行值时，尝试使用空合并运算符

< pre lang =c＃> dr [ EffectiveDate] = effectivedate ?? DBNull.Value;

hi,

i am getting error Cannot set Column 'EffectiveDate' to be null. Please use DBNull instead.
my code is

dt.Columns.Add("EffectiveDate", typeof(DateTime));

   DateTime?   effectivedate=null;


  if (lastRow["Effective_x0020_Date"] != DBNull.Value)
  {

     effectivedate = Convert.ToDateTime(lastRow["Effective_x0020_Date"]);
  }


DataRow dr = dt.NewRow();
     dr["EffectiveDate"] = effectivedate;
dt.Rows.Add(dr);

i followed many things

http://codeverge.com/asp.net.presentation-controls/how-to-return-dbnull.value-inst/487162[^]

but same error i am getting

解决方案

COuld it simply be that lastRow["Effective_x0020_Date"] is DBNull? Then you would have the initial value (null) in effectivedate;

When assigning the data row value, try using null coalescing operator

dr["EffectiveDate"] = effectivedate ?? DBNull.Value;

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