Not able to Render Data table - r

Question

I am trying to render DataTable output to Shiny. Please find below explanation of my use case:
Connected to my database and got table data to df variable.
sent selected input from select input text box to server script.
Server script should take this input and get the data.
ui.R
library(shiny)
library(RODBC)
library(DBI)
# Establishing connection to ORE environment
dbconnect <- odbcConnect("orecloud", uid="XXXX", pwd="XXXXX", believeNRows=FALSE)
# Preparing data frames to get the data and show in select input pick list
df <- data.frame()
df <- sqlQuery(dbconnect,"SELECT distinct cpan FROM TABLE ")
shinyUI(fluidPage(
headerPanel("ORE XXX Summary"),
sidebarLayout(
sidebarPanel(
helpText("Please select Patient Details.."),
selectInput("CPAN",
label = "Choose patient",
choices = df,
selected = NULL),
submitButton(text = "Submit", icon = NULL)),
mainPanel(
dataTableOutput("tableoutput")
)
)
))
server.R
Server script should take the input and query the data from the table
Render the selected data to UI
If I change value in UI then it should display selected input data.
library(RODBC)
shinyServer(
function(input, output) {
dbconnect <- odbcConnect("orecloud", uid="oracle", pwd="Edvenswa2016", believeNRows=FALSE)
df2 <- data.frame()
input_var <- input$CPAN
print (input_var)
my_query <- paste("select * from CYTOKINE where CPAN= ", input_var)
print(myquery)
df2 <- sqlQuery(dbconnect,myquery)
output$tableoutput <- renderDataTable({df2})
}
)

Answer 1

You need to do it reactive
df2=reactive({
input_var <- input$CPAN
my_query <- paste("select * from CYTOKINE where CPAN= ", input_var)
sqlQuery(dbconnect,myquery)
})
and use like renderDataTable({df2()}) } )
If input$CPAN is character you need paste0("select * from CYTOKINE where CPAN= '", input_var,"'")
Also dont forget disconect
session$onSessionEnded(function() {
odbcClose(dbconnect )
})