请更正会话错误 [英] Please correct the error o session

问题描述

大家好，



查看我的代码。它在会话中存储Null值。

Hi Everyone,

Check My code. It stores Null Value in session.

for (int i = 0; i < GridView2.Rows.Count; i++)
        {
          
            string strID  = GridView2.Rows[i].Cells[1].Text;

    


            con.Open();
            using (SqlCommand command = new SqlCommand("select Role_Name from Role2 where Role_ID=@strID", con))
            { 
                SqlParameter param = new SqlParameter();
                param.ParameterName = "@StrID"; param.Value = strID;   
                command.Parameters.Add(param); 
                SqlDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    Session["Role_Name"] = Convert.ToString(reader["Role_Name"]);
                }

            }
            con.Close();
        }

推荐答案

它们之间的基本区别是 Convert.ToString（variable）处理NULL值，即使变量值变为null但 variable.ToString（）将不会处理NULL值，它将引发NULL引用异常错误。因此，使用转换的良好编码实践始终是安全的。 查看更多内容...... [ ^ ]



因此，最好使用 .ToString（）来检查 NULL 值。< br $> b $ b

-KR

The basic difference between them is "Convert.ToString(variable)" handles NULL values even if variable value become null but "variable.ToString()" will not handle NULL values it will throw a NULL reference exception error. So as a good coding practice using "convert" is always safe. see more...[^]

So it's better that you should use .ToString() to check NULL values.

-KR

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