VB.NET Использование в использовании

Question

Могу ли я сделать:

using connection 
myDt1 = sqlSelect(connection, sql) 
myDt2 = sqlSelect(connection, sql) 
end using 

с SQLSelect:

Public Shared Function SQLSelect(ByVal provider As SqlConnection, ByVal strSQL As String, ByVal ParamArray params() As SqlParameter) As DataTable 
Using connection = provider 

SQLSelect = New DataTable 

Dim dtReader As SqlDataReader 
Dim command As SqlCommand = CreateSQLCommand(provider, strSQL, params) 

Try 
    connection.Open() 
    dtReader = command.ExecuteReader() 
    SQLSelect.Load(dtReader) 
    dtReader.Close() 
Catch ex As Exception 
    SQLSelect = Nothing 
Finally 
    'If connection.State = ConnectionState.Open Then 
    ' connection.Close() 
    'End If 
    command.Dispose() 
End Try 

End Using '<--- Here drop connection 
Return SQLSelect 

Поскольку в функции SQLSelect, в конце использования, соединение разрывается! У меня есть ошибка, когда я пытаюсь подключиться ко второму запросу.

Thx

Answer 1

Просто используйте шаблон DAL, как это:

Public Class DataAccessLayer 
    'Implements IDataAccessLayer 

    #Region "Members" 

    Private ReadOnly connectionString As String 
    Private ReadOnly configuration As IConfiguration 
    Private ReadOnly exceptionHandler As IExceptionHandler 

    #End Region 

    #Region "Constructors" 
    Public Sub New() 
     Me.New(New Configuration(), New ExceptionHandler()) 
    End Sub 

    Public Sub New(configuration As IConfiguration, exceptionHandler As IExceptionHandler) 
     ' You can just pass in a ConnectionString, instead of my IConfiguration 
     connectionString = configuration.GetDefaultConnectionString() 
     'Me.exceptionHandler = exceptionHandler 
    End Sub 

    #End Region 

    #Region "Opening and Closing Connection" 

    Public Function GetConnection() As SqlConnection 
     Dim conn = New SqlConnection(connectionString) 
     Try 
      conn.Open() 
     Catch ex As SqlException 
      'exceptionHandler.LogExceptions(ex, Nothing) 
     Catch ex As Exception 
      'exceptionHandler.LogExceptions(ex, Nothing) 
     End Try 
     Return conn 
    End Function 

    #End Region 

    #Region "Stored Procedure Calls" 

    Public Function TestConnection() As Boolean 
     Try 
      Dim conn = New SqlConnection(connectionString) 
      conn.Open() 
      conn.Close() 
     Catch 
      Return False 
     End Try 
     Return True 
    End Function 

    Public Function CallAStoredProcExample() As Boolean 
     Dim codeObject As CodeObject = Nothing 
     Try 
      Using conn = Me.GetConnection() 
       Using sqlCommand = New SqlCommand("sp_GetCodeByCodeID", conn) 
        sqlCommand.CommandType = CommandType.StoredProcedure 
        sqlCommand.Parameters.AddWithValue("@CodeId", 1) 

        Using dr = sqlCommand.ExecuteReader() 
         While dr.Read() 
          codeObject = New CodeObject(dr, True) 
         End While 
        End Using 
       End Using 
      End Using 
     Catch ex As Exception 
      Return False 
     End Try 
     Return True 
    End Function 
End Class 

...

Телефонный код:

Dim DAL = New DataAccessLayer(yourConnectionString, Nothing) 
DAL.CallAStoredProcExample()