Question

我正在尝试根据异步函数中的数据库版本（Oracle或SQL）动态设置我的DbDataReader。 GetReaderAsync函数应该返回DataReader的类型，这样我就可以使用通用阅读器来完成其余的操作。这是我的目的，所以不要觉得有必要修复可能基于错误想法的代码，但确实提供了示例代码来完成需求。目前我收到编译错误ReadAsync is not a member of System.Threading.Tasks.Task(Of System.Data.Common.DbDataReader) 我相信我做错了，可能在GetReaderAsync函数中。

 Using reader As Task(Of Common.DbDataReader) = ConnectionController.GetReaderAsync(command) ' CType(Await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess), Oracle.DataAccess.Client.OracleDataReader)
                    While Await reader.ReadAsync() '<-- Compilation Error
                        If reader.HasRows Then
                        End If
                   End While
End Using



Public Shared Async Function GetReaderAsync(command As DbCommand) As Threading.Tasks.Task(Of DbDataReader)
        'Depending on the XML value provided in the [Provider], then select the appropriate connection from 
        'the object oSettings of the SettingsController. The SettingsController provides a structure called Provider to choose from
        If SettingsController.oSettings.Connection.provider.ToLower = SettingsController.Provider.Oracle Then
            Using reader As Oracle.DataAccess.Client.OracleDataReader = CType(Await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess), Oracle.DataAccess.Client.OracleDataReader)
                command.ExecuteReader()
                Return reader
            End Using
        Else
            Using reader As SqlClient.SqlDataReader = CType(Await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess), SqlClient.SqlDataReader)
                command.ExecuteReader()
                Return reader
            End Using
        End If
    End Function

Answer 1

的工作原理如下：

使用reader As Common.DbDataReader = Await command.ExecuteReaderAsync（CommandBehavior.SequentialAccess）

Answer 2

您可以使用Interface＆＃34; System.Data.IDataReader＆＃34;。我将它用于MySql，MSSql和Sqlite。它非常好。

根据数据库版本选择DataReader类型

2 个答案: