I am taking multiple selection for component as per below code.

selectInput("cmpnt",
            "Choose Component:",
            choices = as.character(levels(Material_Data()$CMPNT_NM)),multiple = TRUE)

But I am trying to write a sql statement as given below, then its not working. Neither it is throwing any error message. When I was selecting one option at a time (without mutiple = TRUE) then it was working (since I was using "=" operator). But after using "multiple=TRUE" I need to use IN operator, which is not working.

Input_Data2 <- fn$sqldf( paste0( "select * from Input_Data1 where MTRL_NBR = '$mtrl1' and CMPNT_NM in ('$cmpnt1')") )

Thanks in advance for any help on this.

Thanks jdharrison! Pleasefind the detailed code:

# server.R
library(RODBC)
library(shiny)
library(sqldf)

Input_Data <- readRDS("InputSource.rds")

Mtrl <- factor(Input_Data$MTRL_NBR)
Mtrl_List <- levels(Mtrl)

shinyServer(function(input, output) {

# First UI input (Service column) filter clientData
output$Choose_Material <- renderUI({
if (is.null(clientData()))
  return("No client selected")
selectInput("mtrl",
            "Choose Material:",
            choices = as.character(levels(clientData()$MTRL_NBR)),
            selected = input$mtrl

)
})

# Second UI input (Rounds column) filter service-filtered clientData
output$Choose_Component <- renderUI({
if(is.null(input$mtrl))
return()

if (is.null(Material_Data()))
  return("No service selected")

selectInput("cmpnt",
            "Choose Component:",
            choices = as.character(levels(Material_Data()$CMPNT_NM)),multiple = TRUE)

})

# First data load (client data)
clientData <- reactive({
#    get(input$Input_Data)
return(Input_Data)
})

# Second data load (filter by service column)
Material_Data <- reactive({
dat <- clientData()
if (is.null(dat))
  return(NULL)
if (!is.null(input$mtrl)) # !
  dat <- dat[dat$MTRL_NBR %in% input$mtrl,]
  dat <- droplevels(dat)
  return(dat)
})

output$Choose_Columns <- renderUI({

if(is.null(input$mtrl))
return()
if(is.null(input$cmpnt))
return()

colnames <- names(Input_Data)

checkboxGroupInput("columns", "Choose Columns To Display The Data:",
                choices  = colnames,
                selected = colnames)
})

output$text <- renderText({ print(input$cmpnt)   })

output$data_table <- renderTable({
 if(is.null(input$mtrl))
  return()

if (is.null(input$columns) || !(input$columns %in% names(Input_Data)))
  return()

Input_Data1 <- Input_Data[, input$columns, drop = FALSE]
cmpnt1 <- input$cmpnt
mtrl1 <- input$mtrl

Input_Data2 <- fn$sqldf( paste0( "select * from Input_Data1 where MTRL_NBR = '$mtrl1'     and CMPNT_NM in ('$cmpnt1')") )
head(Input_Data2, 10)
})
})