title: select input depending on previous select input shiny
body: <p>I have a database and I need to make that in the first selecInput shows the name of 4 diferents columns and according whit the selection, in the next selecIpunt show the categories that correpond to the column selected. I have something like this in my server:</p>
  <pre><code>output$SelectCategory &lt;-renderUI({
     selectInput(&quot;SelectCategory&quot;, &quot;Select Category&quot;,
                 choices = c(&quot;A&quot;=&quot;colname1&quot;,
                             &quot;B&quot;=&quot;colname2&quot;,
                             &quot;C&quot;=&quot;colname3&quot;,
                             &quot;D&quot;=&quot;colname4&quot;)) 
   }) 
   
   output$SelectProc &lt;-renderUI({
     selectInput(&quot;SelectProc&quot;, &quot;Select Procedure&quot;,
                 choices=input$SelectCategory, multiple = T, selected = TRUE) 
  </code></pre>