谁能告诉我这代码错在哪了？关于ACCESS某一个字段显示在textbox上
string strconn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\db1.mdb;";
OleDbConnection conn = new OleDbConnection(strconn);
conn.Open();
string sql = "select [Time] from [project] where [Name]='" + DropDownList1.SelectedValue + "'";
SqlDataReader reader = new SqlDataReader(sql, conn);
if (reader.Read())
{
TextBox3.Text = reader[0].ToString();
}

提示“System.Data.SqlClient.SqlDataReader”不包含采用“2”参数的构造函数 的错误，请问哪里出问题了，应该怎么改？

[解决办法]
SqlDataReader类没有2个参数的构造函数，SqlDataReader reader = new SqlDataReader(sql, conn);改为 SqlDataReader reader = new SqlDataReader(conn);

[解决办法]
MSDN

C# code

private static void ReadOrderData(string connectionString){    string queryString =        "SELECT OrderID, CustomerID FROM dbo.Orders;";    using (SqlConnection connection =               new SqlConnection(connectionString))    {        SqlCommand command =            new SqlCommand(queryString, connection);        connection.Open();        SqlDataReader reader = command.ExecuteReader();        // Call Read before accessing data.        while (reader.Read())        {            Console.WriteLine(String.Format("{0}, {1}",                reader[0], reader[1]));        }        // Call Close when done reading.        reader.Close();    }}
[解决办法]
SqlDataReader reader = new SqlDataReader(sql, conn);
改成
OleDbCommand cmd=new OleDbCommand(sql.conn);
OleDbDataReader reader=cmd.ExecuteReader();
[解决办法]
string strconn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\db1.mdb;";
  OleDbConnection conn = new OleDbConnection(strconn);
  conn.Open();
  string sql = "select [Time] from [project] where [Name]='" + DropDownList1.SelectedValue + "'";
 OleDbCommand cmd=new OleDbCommand(sql.conn);
OleDbDataReader reader=cmd.ExecuteReader();
  if (reader.Read())
  {
  TextBox3.Text = reader[0].ToString();
  }
conn.Close();