library(shiny)
library(DBI)
ui <- fluidPage(
 textInput("ID", "Enter your ID:", "5"),
  tableOutput("tbl")
)

server <- function(input, output, session) {
output$tbl <- renderTable({
conn <- dbConnect(
  drv = RMySQL::MySQL(),
  dbname = "shinydemo",
  host = "shiny-demo.csa7qlmguqrf.us-east-1.rds.amazonaws.com",
  username = "guest",
  password = "guest")
on.exit(dbDisconnect(conn), add = TRUE)
query <- paste0("SELECT * FROM City WHERE ID = '", input$ID, "';")
dbGetQuery(conn, query)
  })
}

shinyApp(ui, server)