c# - 用 oledb 填充数据集时出错

Question

我正进入（状态

“没有为一个和多个必需参数指定值”

从下面的代码看起来一切都很好，无法找到问题。

 string myConnectionString= @"Provider=Microsoft.Jet.OLEDB.4.0; Data source=D:\TiptonDB.mdb";
                string query = "SELECT NodeID FROM NDDINodes";//"SELECT O.NodeID, N.NodeID FROM NDDINodes AS N, NDDINodes AS O WHERE N.X=O.X And N.Y=O.Y And N.NodeID<>O.NodeID";

                DataSet dt = new DataSet();
                using (OleDbConnection myConnection = new OleDbConnection())
                {
                    myConnection.ConnectionString=myConnectionString;
                    OleDbCommand cmd=new OleDbCommand ();
                    cmd.Connection=myConnection;

                 //   cmd.CommandText="SELECT O.NodeID, N.NodeID FROM NDDINodes AS N, NDDINodes AS O WHERE N.X=O.X And N.Y=O.Y And N.NodeID<>O.NodeID";
                    myConnection.Open();
                    OleDbDataAdapter ad = new OleDbDataAdapter(query,myConnection);
                    ad.Fill(dt);
                }

Answer 1

string myConnectionString= @"Provider=Microsoft.Jet.OLEDB.4.0; Data source=D:\TiptonDB.mdb";
                string query = "SELECT NodeID FROM NDDINodes";//"SELECT O.NodeID, N.NodeID FROM NDDINodes AS N, NDDINodes AS O WHERE N.X=O.X And N.Y=O.Y And N.NodeID<>O.NodeID";

DataSet dt = new DataSet();

OleDbConnection objXConn = new OleDbConnection(myConnectionString);
                objXConn.Open();
                OleDbCommand objCommand = new OleDbCommand(query, objXConn);
                OleDbDataAdapter adp = new OleDbDataAdapter(objCommand);
                adp.Fill(dt);
                objXConn.Close();

Answer 2

只需将其添加到您的代码中

  OleDbDataAdapter ad = new OleDbDataAdapter();
ad.SelectCommand = new OleDbCommand(query, myConnection);

Answer 3

确保您的连接字符串没有丢失数据：UserName/Password, Persist Security Info=True,...

检查此链接以访问 connectionString 设置。