---
title: "zdelta"
slug: "zdelta"
updated: 2022-11-08T13:15:44Z
published: 2022-11-08T13:15:44Z
canonical: "docs.datajet.app/zdelta"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.datajet.app/llms.txt
> Use this file to discover all available pages before exploring further.

# zdelta

## PostFunction: [zdelta]

#### Returns the difference between current row and previous row for the specified measure.

i.e., Subtracts the previous row from the current row.

First row is 0.00

Note: to have first row returned as null, see **PostFunction: delta**

#### 

## Purpose

Use this function to:

- See how a measure changes from one row to the next
- Calculate changes from one reporting period to the next

## Calculation

```actionscript
zdelta = Row(X) - Row(X-1)

Row(X) = "value for current row"
Row(X-1) = "value for previous row"
zdelta= Row(X) - Row(X-1)
```

## Sample Result

![zdelta_sample](https://cdn.document360.io/73b6469b-c1e4-47e9-aa65-986c8ebd17ca/Images/Documentation/zdelta_sample.PNG)

## Parameters

| Input | Description |
| --- | --- |
| **Dimensions** | Discrete field(s). All fields must come from the same table. |
| **Name** | Name to be displayed as Column Header in result grid |
| **Measure** | The field to be used in the post-function calculation. Must be numeric if Function is anything other than COUNT. Must come from same table as DIMENSIONS. Supports Discrete or Continuous DataTypes. |
| **Function** | COUNT / SUM / AVG / MIN / MAX / STDEV |
| **PostFunction** | **zdelta** |
| ***Value*** | Optional. Filter to apply when evaluating FUNCTION. Only records in the Filter Recordset will be included in the Function and Post-Function calculations. Must come from same table as DIMENSION/MEASURE or be linked to the Dimension table. |
| ***Axis*** | 0 / 1. Y-Axis to use when plotting graph. Default = 0 |
| ***Plot*** | Y / N. Specifies whether measure’s output column should be plotted on graph. Default = Y |
| ***Resolve*** | Optional. Resolve level for the measure. If blank, Resolve = Dimension Table |
| ***Series Type*** | Default / Bar / Stacked Bar / Line / Spline / RangeLow / RangeHigh / CSLow / CSHigh / CSOpen / CSClose Determines the graph style for the measure. |
| ***Popup*** | Default / None / Extended |
| ***Prefix*** | $ / £ / E / % |

## Usage Notes

The order of the dimensions is important as this will affect the inter-row calculations. Sort by Label or Value, Ascending or Descending.

Can be used with multiple dimensions as calculates difference between each row.

## Example

Calculate difference in sales from one month to the next (Month on Previous Month)

*e.g Sales difference by month*

Table: Transactions

Dimension: [Transactions].[YearMonth]

Measure: [Transactions].[CastPrice], SUM, **zdelta**

NoteMeasure 1 is included purely for illustration. It is not necessary to include this measure for the calculation to work.

| Dimension(s): | [transactions].[yearmonth] |
| --- | --- |
| Measure 1 | - Name: =Sales This Month - Measure: = transactions.castprice - Function: =sum - Post: = - Value: = | - Axis: =0 - Plot:=Y - Resolve:= - Series Type:=Line - Popup:=Default - Prefix:= |
| Measure 2 | - Name: =Monthly Change - Measure: =transactions.castprice - Function: =sum - **Post: =zdelta** - Value: = | - Axis: =0 - Plot:=Y - Resolve:= - Series Type:=Bar - Popup:=Default - Prefix:= |

### **![zdelta_example1](https://cdn.document360.io/73b6469b-c1e4-47e9-aa65-986c8ebd17ca/Images/Documentation/zdelta_example1.png) ![zdelta_example2](https://cdn.document360.io/73b6469b-c1e4-47e9-aa65-986c8ebd17ca/Images/Documentation/zdelta_example2.png)** See Also:

- [Engineering](/v1/docs/engineering)
- [Post Functions - Overview](/v1/docs/post-functions-overview)
- [delta](/v1/docs/postfunction-delta)