获取sqlcommand的值 [英] get value of sqlcommand

问题描述

亲爱的，

这是我的代码：

 SqlDataReader dReader; 
 SqlConnection conn =  new  SqlConnection（ @ 数据源= .\sql2008;初始目录= jelvehsadb;集成安全性=真;）; 
 SqlCommand comm =  new  SqlCommand（）; 
 comm.Connection = conn; 
 
 comm.CommandText =  @ 从work_with_us中选择响应，其中national_code = @ CustomerID; 
 comm.Parameters.AddWithValue（  CustomerID， 00488 ）; 
 comm.Connection.Open（）; 
 
 
 dReader = comm.ExecuteReader（）; 
 
  if （dReader.HasRows ==  true ）
 { 
 TxtShow.Text = ???; 
} 
 
 
} 

我的问题是如何从dreader获得我的回复？

结果必须在txtshow上显示。

谢谢

解决方案

尝试：

  if （dReader.Read（））
 {
 TxtShow.Text =（ string ）reader [  response]; 
} 

但在步骤2中我的sqlcommand返回一个值，它与响应列无关，

所以我想在datareader上准备好访问该值，你可以帮我看看如何访问这些数据，

谢谢dera OriginalGriff





是的，它是！

当你的问题发生时SELECT，SQL返回与WHILE语句匹配的所有行，但仅返回您指定的列。所以如果你有一个包含三列的表：

 Id UserName UserAddress 
 7 Fred Home 
 8 Joe Away 
 9 Bert Holiday小屋

你发出一个SELECT：

 SELECT UserName，UserAddress FROM MyTable WHERE Id = 8 

然后，您需要对DataReader进行两次访问，以读取您要求的行的两列中的每一列：

  string  userName =（ string ）reader [ 用户名]; 
  string  userAddr =（ string ）reader [   UserAddress]; 
 

在你的情况下，你要求（我假设）一行（national_code为488）和一栏：回复。



这有意义吗？或者我们在这里交叉目的？

你好会员，



你可以修改你的代码，如下所示。 />

 SqlDataReader dReader; 
 
 SqlConnection conn =  new  SqlConnection（ @  Data Source = .\sql2008; Initial Catalog = jelvehsadb; Integrated Security = True;）; 
 SqlCommand comm =  new  SqlCommand（）; 
 comm.Connection = conn; 
 
 comm.CommandText =  @ 从work_with_us中选择响应，其中national_code = @ CustomerID; 
 comm.Parameters.AddWithValue（  CustomerID， 00488 ）; 
 comm.Connection.Open（）; 
 
 dReader = comm.ExecuteReader（）; 
  //   SqlDataReader的默认位置在第一条记录之前。  
  //  因此，您必须调用Read才能开始访问任何数据。 
  if （dReader.Read（））{
 TxtShow.Text = dReader.GetString（ 0 ）; 
} 

问候，

你可以这样做：

 SqlDataReader drmax1; 
 drmax = comm.ExecuteReader（）; 
 drmax.Read（）; 
 TxtShow.Text = System.Convert.ToString（（System.Convert.ToInt32（drmax [  response ]的ToString（）））; 

hi dear's,
this is my code:

SqlDataReader dReader;
        SqlConnection conn = new SqlConnection(@"Data Source=.\sql2008;Initial Catalog=jelvehsadb;Integrated Security=True;");
        SqlCommand comm = new SqlCommand();
        comm.Connection = conn;

        comm.CommandText = @"Select response from work_with_us where national_code =@CustomerID";
        comm.Parameters.AddWithValue("CustomerID", 00488);  
        comm.Connection.Open();
        

        dReader = comm.ExecuteReader();
          
        if (dReader.HasRows == true)
        {
            TxtShow.Text = ???;
        }
        

    }

my problem is how i can get my response vlaue from dreader??
the result must show on txtshow.
thanks

解决方案

Try:

if (dReader.Read())
   {
   TxtShow.Text = (string) reader["response"];
   }

"but in step 2 when my sqlcommand return a value,it's not related to the response column,
so i want access to that value is now ready on the datareader,may you help me how i can access to this data,
thanks dera OriginalGriff"


Yes, it is!
When your issue a SELECT, SQL returns all the rows that match the WHILE statement, but only the columns you specify. So if you have a table with three columns:

Id   UserName  UserAddress
7    Fred      Home
8    Joe       Away
9    Bert      Holiday cottage

And you issue a SELECT:

SELECT UserName, UserAddress FROM MyTable WHERE Id=8

Then you need to do two accesses to your DataReader to read each of the two columns of the row that you have asked for:

string userName = (string) reader["UserName"];
string userAddr = (string) reader["UserAddress "];

In your case, you are asking for (I assume) a single row (where the national_code is 488) and a single column: response.

Does that make sense? Or are we talking at cross purposes here?

Hello Member,

You can modify your code as shown below.

SqlDataReader dReader;

SqlConnection conn = new SqlConnection(@"Data Source=.\sql2008;Initial Catalog=jelvehsadb;Integrated Security=True;");
SqlCommand comm = new SqlCommand();
comm.Connection = conn;
 
comm.CommandText = @"Select response from work_with_us where national_code =@CustomerID";
comm.Parameters.AddWithValue("CustomerID", 00488);  
comm.Connection.Open();
        
dReader = comm.ExecuteReader();
// The default position of the SqlDataReader is before the first record. 
// Therefore, you must call Read to begin accessing any data.
if (dReader.Read()) {
    TxtShow.Text = dReader.GetString(0);
}

Regards,

you can do something like this :

SqlDataReader drmax1;
 drmax = comm.ExecuteReader();
                    drmax.Read();
                    TxtShow.Text = System.Convert.ToString((System.Convert.ToInt32(drmax["response"].ToString()));

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