从表中显示网站行

I have created a local database in Visual Studio 2010 and a web application which interacts with it. I want to create a search function in order to obtain some rows from a table. I have a text field where i write a date (delivery date for a product, for example) and a button. On clicking the button, i want to bring on my web page information about an invoice. Please, check out my code:

我在Visual Studio 2010中创建了一个本地数据库和一个与之交互的web应用程序。我想创建一个搜索函数，以便从表中获取一些行。我有一个文本字段，我在其中编写一个日期(例如，产品的交付日期)和一个按钮。点击按钮时，我想打开关于发票的网页信息。请检查我的代码:

SqlConnection con = new SqlConnection(@"Data Source=JOHN-PC\SQLEXPRESS;Initial Catalog=subiect1;Integrated Security=True");
try
{
    con.Open();
    DataSet datas = new DataSet();
    SqlDataAdapter adapter = new SqlDataAdapter("select * from Factura where Data_Livrare = @Data_Livrare", con);
    SqlCommandBuilder commandBuilder = new SqlCommandBuilder(adapter);
    commandBuilder.Parameters.Add(new SqlParameter("@Data_Livrare", (object)txtData.Text));
    SqlDataReader reader = reader.ExecuteReader();
    while (reader.Read())
    {                   
        adapter.Fill(datas);
    }                
}
catch (Exception ex)
{
    Label3.Text = "Error --> " + ex.Message;
}
finally
{
    con.Close();
}

I get the error:

我得到了错误:

"A using namespace directive can only be applied to namespaces; System.Data.SqlClient.SqlCommand is a type, not a namespace".

If i delete the System.Data.SqlClient.SqlCommand directive, i get plenty of errors referring to some methods which are, apparently, undefined (such as Parameters from commandBuilder.Parameters.Add and ExecuteReader()). When i run the program in browser, complete the textfield and click the button, i get:

如果我删除了System.Data.SqlClient。SqlCommand指令，我在引用一些显然没有定义的方法(比如commandbuild .Parameters)时得到了大量错误。添加和ExecuteReader())。当我在浏览器中运行程序，完成textfield，点击按钮，我得到:

" Fill: SelectCommand.Connection property has not been initialized."

What am i missing here? Is it only the user directive wrong or i simply don't approach well this problem?

我错过了什么?是用户指令错了，还是我没有很好地解决这个问题?

I must mention I am a beginner in C#.

我必须提一下，我是c#的初学者。

1 个解决方案

#1

Check your using clauses at the top of your code.

在你的代码顶部检查你的使用条款。

I think you have using System.Data.SqlClient.SqlCommand;

我认为你已经使用System.Data.SqlClient.SqlCommand;

You should have System.Data.SqlClient;

你应该System.Data.SqlClient;

If you check the MSDN docs you will see that the namespace for System.Data.SqlClient.SqlCommand is System.Data.SqlClient

如果您检查MSDN文档，您将看到System.Data.SqlClient的名称空间。SqlCommand是System.Data.SqlClient

#1