请做过C3+ORACLE的朋友进来解决问题

[skyno1]

OracleConnection OracConn=new OracleConnection(OracleStr);
OracleCommand Dap= new OracleCommand(" SELECT * FROM Orpub.OPERGROUPMOD where 1=1 and OperParentId=:uid Order By OperId,OperParentId ", OracConn );
OracConn.Open();

OracleDataReader DReader;//=new OracleDataReader();
Dap.CommandType= CommandType.Text;
Dap.Parameters.Add( new OracleParameter("uid",OracleType.VarChar,6,"OperParentId"));
Dap.Parameters["uid"].Value="NULL";

MessageBox.Show(Dap.CommandText);
DReader=Dap.ExecuteReader();
当我运行到DReader=Dap.ExecuteReader();就出错误,我现在确定错误是出现在
Dap.Parameters.Add( new OracleParameter("uid",OracleType.VarChar,6,"OperParentId"));
Dap.Parameters["uid"].Value="NULL";
这两句上了,
我用的数据库是ORACLE9I的,大家帮帮忙给解决下,谢谢

[haixj]

Dap.Parameters["uid"].Value="NULL";
改為Dap.Parameters["uid"].Value=DBNull.Value試試