从数据库检索信息 [英] retrieve information from database

问题描述

你好

我需要从数据库中检索信息
我应该使用什么代码

hello

I need to retrieve information from database
what the code I should use

string ip;
                        ip = GetIP();
                        SqlCommand command = new SqlCommand("SELECT DeviceName FROM ConnectedDevice  WHERE IP= @IP AND IDName=@IDName  ", connection);
                        command.Parameters.Add(new SqlParameter("@IP", ip));
                        command.Parameters.Add(new SqlParameter("@IDName", name));
                        command.ExecuteNonQuery();

                        SqlDataReader reader1 = command.ExecuteReader();
                         if (reader1.HasRows)
                            {

                                device = reader1.GetValue(0).ToString();
                                
                              
                            }

代码

the code

device = reader1.GetValue(0).ToString();

不要检索任何东西并给出错误
我应该用??替换什么代码?

谢谢:)

do not retrieve any thing and give an error
what the code should I replace it with ??

thanks :)

推荐答案

在这里看看: ^ ]-在页面底部，您将找到一个解决方案:如何从datareader读取数据?

Take a look here: SqlDataReader Class[^] - on the bottom of page you''ll find a solution: how to read data from datareader?

要开始选择声明，替换

To start for a select statement, replace

command.ExecuteNonQuery();

与

with

SqlDataAdapter sqlDa = new SqlDataAdapter(command);
DataSet ds= new DataSet();
sqlDa.Fill(ds);

此
的状态

if (reader1.HasRows)
{
       device = reader1.GetValue(0).ToString();
}

写这个

Write this

if (reader1.HasRows)
{
   if(reader1.Read())
   {
       device = reader1.GetValue(0).ToString();
   }
}

您可以删除此行(删除此行)

and you can remove this line(delete this line)

command.ExecuteNonQuery();

这篇关于从数据库检索信息的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！