title: ADF expression to convert array to comma separated string
body: <p>This appears to be pretty basic but I am unable to find a suitable pipeline expression function to achieve this.</p>
  
  <p>I have set an array variable VAR1 with the following value, which is an output from a SQL Lookup activity in an ADF pipeline:</p>
  
  <pre><code>[
      {
          "Code1": "1312312"
      },
      {
          "Code1": "3524355"
      }
  ]
  </code></pre>
  
  <p>Now, I need to convert this into a comma separated string so I can pass it to a SQL query in the next activity - something like:</p>
  
  <p><code>"'1312312','3524355'"</code></p>
  
  <p>I am unable to find an expression function to iterate over the array elements, nor convert an array to a string. The only pipeline expression functions I see are to convert string to array and not the other way around.</p>
  
  <p>Am I missing something basic? How can this be achieved?</p>