.net - Connection关闭时DataReader没有关闭，后果？

Question

例如我有这段代码:

Sub Month()
    Dim Conn As New Data.OracleClient.OracleConnection
    Conn.Open()
    Try

        Dim Cmd As New Data.OracleClient.OracleCommand
        With Cmd
            .Connection = Conn
            .CommandType = Data.CommandType.Text
            .CommandText = "SELECT * FROM MONTH"
        End With
        Dim datareader As Data.OracleClient.OracleDataReader = Cmd.ExecuteReader
        While datareader.Read
            Response.Write(datareader(0))
        End While
    Catch ex As Exception
        Throw ex
    Finally
        Conn.Close()
    End Try
End Sub

当连接关闭(Conn.close)时，datareader 会发生什么

datareader 使用的 Cursor 会被释放吗？还是会保持开放？

如果数据读取器使用的游标仍然打开，它什么时候会自动关闭？还是我应该手动关闭它？

它会导致可怕的“ORA-01000: maximum open cursors exceeded”吗？

提前致谢

Answer 1

您应该在 using block 中创建对象，以便正确处理它们:

Using Conn As New Data.SqlClient.SqlConnection
    Conn.Open()

    Dim Cmd As New Data.SqlClient.SqlCommand
    With Cmd
        .Connection = Conn
        .CommandType = Data.CommandType.Text
        .CommandText = "SELECT * FROM MONTH"
    End With

    Using datareader As Data.SqlClient.SqlDataReader = Cmd.ExecuteReader()
        While datareader.Read()
            Response.Write(datareader(0))
        End While
    End Using
End Using

无需在连接或数据读取器上调用 Close。