Question

ExecuteReader：Connection属性有尚未初始化。

我的编码是

protected void Button2_Click(object sender, EventArgs e)
    {

       SqlConnection conn = new SqlConnection("Data Source=Si-6\\SQLSERVER2005;Initial Catalog=rags;Integrated Security=SSPI");

    SqlDataReader rdr = null;

    try
    {
        // 2. Open the connection
        conn.Open();

        // 3. Pass the connection to a command object
        //SqlCommand cmd = new SqlCommand("select * from Customers", conn);
        SqlCommand cmd=new SqlCommand ("insert into time(project,iteration)
                  values('"+this .name1 .SelectedValue +"','"+this .iteration .SelectedValue +"')");

        //
        // 4. Use the connection
        //

        // get query results
        rdr = cmd.ExecuteReader();

        // print the CustomerID of each record
        while (rdr.Read())
        {
            Console.WriteLine(rdr[0]);
        }
    }
    finally
    {
        // close the reader
        if (rdr != null)
        {
            rdr.Close();
        }

        // 5. Close the connection
        if (conn != null)
        {
            conn.Close();
        }
    }
  }
  }

    }

Answer 1

使用它并传递连接对象：

 SqlCommand cmd=new SqlCommand ("insert into time(project,iteration)values('"+this .name1 .SelectedValue +"','"+this .iteration .SelectedValue +"')",conn);

Answer 2

SqlCommand cmd=new SqlCommand ("insert into time(project,iteration)values('....之后添加

cmd.Connection = conn;

希望这个帮助

Answer 3

您必须为命令对象分配连接，例如..

SqlCommand cmd=new SqlCommand ("insert into time(project,iteration)values('"+this .name1 .SelectedValue +"','"+this .iteration .SelectedValue +"')");
cmd.Connection = conn;

Answer 4

所有的答案都是真的。这是另一种方式。我喜欢这一个

SqlCommand cmd = conn.CreateCommand()

你必须注意到字符串concat有一个sql注入问题。使用参数 http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.parameters.aspx

Answer 5

你也可以这样写：

SqlCommand cmd=new SqlCommand ("insert into time(project,iteration) values (@project, @iteration)", conn);
cmd.Parameters.AddWithValue("@project",name1.SelectedValue);
cmd.Parameters.AddWithValue("@iteration",iteration.SelectedValue);

Answer 6

如前所述，您应该分配连接，最好也应该使用sql参数，因此您的命令赋值将为：

    // 3. Pass the connection to a command object
    SqlCommand cmd=new SqlCommand ("insert into time(project,iteration) values (@project, @iteration)", conn); // ", conn)" added
    cmd.Parameters.Add("project", System.Data.SqlDbType.NVarChar).Value = this.name1.SelectedValue;
    cmd.Parameters.Add("iteration", System.Data.SqlDbType.NVarChar).Value = this.name1.SelectedValue;

    //
    // 4. Use the connection
    //

通过使用参数可以避免SQL注入和其他有问题的拼写错误（项目名称如“myproject's”就是一个例子）。

Answer 7

我喜欢将所有sql连接放在using语句中。我认为它们看起来更干净，当你完成它们之后它们会自行清理。我还建议参数化每个查询，不仅更安全，而且如果您需要返回并进行更改，则更容易维护。

// create/open connection
using (SqlConnection conn = new SqlConnection("Data Source=Si-6\\SQLSERVER2005;Initial Catalog=rags;Integrated Security=SSPI")
{
    try
    {
        conn.Open();

        // initialize command
        using (SqlCommand cmd = conn.CreateCommand())
        {

            // generate query with parameters
            with cmd
            {
                .CommandType = CommandType.Text;
                .CommandText = "insert into time(project,iteration) values(@name, @iteration)";
                .Parameters.Add(new SqlParameter("@name", this.name1.SelectedValue));
                .Parameters.Add(new SqlParameter("@iteration", this.iteration.SelectedValue));
                .ExecuteNonQuery();
            }
        }
    }
    catch (Exception)
    {
        //throw;
    }
    finally
    {
        if (conn != null && conn.State == ConnectionState.Open)
        {
            conn.Close;
        }
    }
}

ExecuteReader：尚未初始化Connection属性

7 个答案: