{
  "columns": [
    "currentAmount",
    "priorAmount",
    "difference",
    "changeRate"
  ],
  "calculatedFields": [
    {
      "name": "currentAmount",
      "expression": "sum(if(invoiceMonth == '2012-11', invoiceAmount, 0))"
    },
    {
      "name": "priorAmount",
      "expression": "sum(if(invoiceMonth == '2012-10', invoiceAmount, 0))"
    },
    {
      "name": "difference",
      "expression": "sum(if(invoiceMonth == '2012-11', invoiceAmount, 0)) - sum(if(invoiceMonth == '2012-10', invoiceAmount, 0))"
    },
    {
      "name": "changeRate",
      "expression": "(sum(if(invoiceMonth == '2012-11', invoiceAmount, 0)) - sum(if(invoiceMonth == '2012-10', invoiceAmount, 0))) / nullif(sum(if(invoiceMonth == '2012-10', invoiceAmount, 0)), 0)"
    }
  ],
  "slice": [
    {
      "field": "invoiceDate",
      "op": "[)",
      "value": [
        "2012-10-01",
        "2012-11-16"
      ]
    },
    {
      "field": "invoiceDayOfMonth",
      "op": "<=",
      "value": 15
    }
  ],
  "limit": 1
}