db <- dbConnect(MySQL(), dbname = "rstudio", host = "localhost",
                    port = 3306, user = "root", password = "")

query <- sprintf("SELECT * FROM userdetails where SSC = %s",input$tenth)

data <- dbGetQuery(db, query)

Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)