server <- function(input, output) {
  aktiver_filter <- reactive({
    if (input$filter_giro  > 0 && 
        input$filter_giro  == max(input$filter_giro, input$filter_monat, input$filter_alle))
      "giro"
    else if (input$filter_monat > 0 && 
        input$filter_monat == max(input$filter_giro, input$filter_monat, input$filter_alle))
      "monat"
    else
      "alle"
  })
  buchungenServer("buchungen_tab", conn, aktiver_filter = aktiver_filter) 
  
}