ExecuteReader:连接属性尚未初始化

ExecuteReader: Connection property has not been initialized.

ExecuteReader:连接属性尚未初始化。

my coding is

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();
        }
    }
  }
  }

    }

7 个解决方案

#1

use this and pass connection object :

使用这个并传递连接对象:

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

#2

After SqlCommand cmd=new SqlCommand ("insert into time(project,iteration)values('.... Add

后SqlCommand cmd = new SqlCommand(“插入时间(项目,迭代)值(“....添加

cmd.Connection = conn;

Hope this help

希望这有助于

#3

you have to assign connection to your command object, like..

您必须将连接分配给命令对象，比如…

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

#4

All of the answers is true.This is another way. And I like this One

所有的答案都是正确的。这是另一种方式。我喜欢这个。

SqlCommand cmd = conn.CreateCommand()

you must notice that strings concat have a sql injection problem. Use the Parameters http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.parameters.aspx

您必须注意到string concat有sql注入问题。使用http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.parameters.aspx的参数

#5

You can also write this:

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);

#6

As mentioned you should assign the connection and you should preferably also use sql parameters instead, so your command assignment would read:

如前所述，您应该分配连接，最好也使用sql参数，因此您的命令分配应该是:

    // 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
    //

By using parameters you avoid SQL injection and other problematic typos (project names like "myproject's" is an example).

通过使用参数，您可以避免SQL注入和其他有问题的拼写错误(例如“myproject”之类的项目名称)。

#7

I like to place all my sql connections in using statements. I think they look cleaner, and they clean up after themselves when your done with them. I also recommend parameterizing every query, not only is it much safer but it is easier to maintain if you need to come back and make changes.

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，当你用完后它们会自己清理。我还建议对每个查询进行参数化，这不仅更安全，而且如果需要返回并进行更改，维护起来也更容易。

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