在C＃中将oledbdatareader转换为dbdatareader

本文介绍了在C＃中将oledbdatareader转换为dbdatareader的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

如何在C＃中动态地将System.Data.OleDb.OleDbDataReader转换为System.Data.Common.DbDataReader

public T GetProjectCodes< t> （字符串Args） { string strProjects =; string QryAllProject =select * from tbl_Project_Details; if（Args ==S） { strProjects = MyTest.GetRecordString（gcnPROJECT，QryAllProject，*，\ n）; return（T）Convert.ChangeType（strProjects，typeof（T））; } else { DbDataReader Dr = null; Dr = MyTest.GetDataReader（gcnPROJECT，QryAllProject）; //此函数返回Dbdatareader // return（T）Convert.ChangeType（Dr，typeof（T））; // return（T）Convert.ChangeType（Dr，typeof（Dr））; return（T）Convert.ChangeType（Dr，typeof（T））; } // return（T）strProjects; } public static DbDataReader GetDataReader（DbConnection myConnection，string strQry） { DbDataReader ObjmyReader0 = null; DbDataReader ObjmyReader = null; string RetVal = string.Empty; DbCommand myCommand = null; myCommand =（DbCommand）myConnection.CreateCommand（）; // myCommand.CommandText =SELECT * FROM Dept; myCommand.CommandText = strQry; if（myConnection.State == ConnectionState.Closed || myConnection.State == ConnectionState.Broken）{ myConnection.Open（）; } 尝试 { if（ObjmyReader！= null） { if（ObjmyReader.IsClosed == false） { ObjmyReader.Close（）; } } ObjmyReader =（DbDataReader）myCommand.ExecuteReader（System.Data.CommandBehavior.CloseConnection）; } catch（Exception rdExc） { if（（ObjmyReader！= null）&&（ObjmyReader.IsClosed == false）） { ObjmyReader.Close（）; ObjmyReader =（DbDataReader）myCommand.ExecuteReader（）; } } 最后 { myCommand.Dispose（）; ObjmyReader0 = ObjmyReader; // ObjmyReader.Close（）; } 返回ObjmyReader0; // return（DbDataReader）Convert.ChangeType（ObjmyReader0，typeof（DbDataReader））; ObjmyReader0.Dispose（）; }

请检查并指导我... 谢谢 vilas

解决方案

你为什么要那样做？ OleDbDataReader 继承自 DbDataReader 类（参见 MSDN [ ^ ]），因此您可以直接退货，不需要任何转换 。

Hi, how to convert System.Data.OleDb.OleDbDataReader to System.Data.Common.DbDataReader dynamically in C#

public T GetProjectCodes<t> (string Args) { string strProjects = ""; string QryAllProject ="select * from tbl_Project_Details"; if (Args == "S") { strProjects = MyTest.GetRecordString(gcnPROJECT, QryAllProject, "*", "\n"); return (T)Convert.ChangeType(strProjects, typeof(T)); } else { DbDataReader Dr = null; Dr = MyTest.GetDataReader(gcnPROJECT, QryAllProject);// this function returns Dbdatareader //return (T)Convert.ChangeType(Dr, typeof(T)); //return (T)Convert.ChangeType(Dr, typeof(Dr)); return (T)Convert.ChangeType(Dr, typeof(T)); } // return (T) strProjects; } public static DbDataReader GetDataReader(DbConnection myConnection, string strQry) { DbDataReader ObjmyReader0 = null; DbDataReader ObjmyReader = null; string RetVal = string.Empty; DbCommand myCommand = null; myCommand = (DbCommand)myConnection.CreateCommand(); // myCommand.CommandText = "SELECT * FROM Dept"; myCommand.CommandText = strQry; if (myConnection.State == ConnectionState.Closed || myConnection.State == ConnectionState.Broken) { myConnection.Open(); } try { if (ObjmyReader != null) { if (ObjmyReader.IsClosed == false) { ObjmyReader.Close(); } } ObjmyReader = (DbDataReader)myCommand.ExecuteReader(System.Data.CommandBehavior.CloseConnection); } catch (Exception rdExc) { if ((ObjmyReader != null) && (ObjmyReader.IsClosed == false)) { ObjmyReader.Close(); ObjmyReader = (DbDataReader)myCommand.ExecuteReader(); } } finally { myCommand.Dispose(); ObjmyReader0 = ObjmyReader; // ObjmyReader.Close(); } return ObjmyReader0; //return (DbDataReader)Convert.ChangeType(ObjmyReader0, typeof(DbDataReader)); ObjmyReader0.Dispose(); }

Please check and guide me... thanks vilas

解决方案

Why would you want to do that? The OleDbDataReader inherits from DbDataReader class (see MSDN[^]) , hence you may return it directly, without any ''conversion''.