如何检查null在datarow行在c＃ [英] how to check for null in datarow row in c#

问题描述

我有此代码

  foreach（DTgraph.Rows中的DataRow行）
 {
 String UserName = row [UserName]。ToString（）; 
 String LoggedState = row [LoggedState]。ToString（）; 
 String InteractionId = row [InteractionId]。ToString（）; 
 String InteractionType = row [InteractionType]。ToString（）; 
 
} 
  

如何检查 [something] 为null？

我试图运行代码，空值变为（空）。

我现在这是一个愚蠢的问题，但我的问题是，我正在做 ToString（）所以我认为null变成 null 或 NULL 或 code>还是空的？

感谢

解决方案 DBNull.Value

  var UserName = row [UserName]。ToString 
  

到

  var UserName = reader [UserName]！= DBNull.Value？ row [UserName]。ToString（）：; 
  

更新

  var UserName =; 
 if（reader [UserName]！= DBNull.Value）
 {
 UserName = row [UserName]。ToString 
} 
  

I have this code

  foreach (DataRow row in DTgraph.Rows)
            {
                String UserName = row["UserName"].ToString();
                String LoggedState = row["LoggedState"].ToString();
                String InteractionId = row["InteractionId"].ToString();
                String InteractionType = row["InteractionType"].ToString();

            }

how to check if the row["something"] is null?

I tried to run the code, and the null values becomes "" (empty).

I need to check if these is null.

I now that this is an stupid question, but my problem is that I am making ToString() so i thought that null becomes null or NULL or Null or empty?

thanks

解决方案

use DBNull.Value

 var UserName = row["UserName"].ToString();

to

 var UserName =  reader["UserName"] != DBNull.Value ? row["UserName"].ToString():"";

Update

 var UserName = "";
 if(reader["UserName"] != DBNull.Value)
 {
     UserName = row["UserName"].ToString();
 }

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