---
title: "DAYSBEFOREMAX(A)"
slug: "engineeringdatefunction2-9"
updated: 2021-10-14T15:11:38Z
published: 2021-10-14T15:11:38Z
canonical: "docs.datajet.app/engineeringdatefunction2-9"
---

> ## 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.

# DAYSBEFOREMAX(A)

## Date Transform: DAYSBEFOREMAX(A)

## Returns the difference in days between A and Max(A)

## Purpose

Use this function to calculate:

- The number of days that elapsed between an event and the latest occurrence of that event
- The number of days a transaction occurred before the latest transaction

## Return Value

| Property | Value |
| --- | --- |
| **FieldType** | Integer |
| **FieldSize** | Med |
| **DataType** | Discrete |
| **DataSize** | Short |

```shell
Example Return Value: 0....N   
where 
N is the maximum number of days between the earliest and latest date in the dataset
```

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

## Parameters

| Parameter | JSON | Description |
| --- | --- | --- |
| **Table** | “targetTable”: “MyTableName” | The target table on which the new field will be created |
| **Filter** | “dataset”: {DataSet_JSON} | Optional. If a filter is applied, records not in the filter Recordset will be returned as null. |
| **DateTimeFunction** | “p1”: “DAYSBEFOREMAX(A)” | DAYSBEFOREMAX(A) |
| **A** | “p2”: “DateFieldName” | Required. The date field from which to take the minimum value and the comparator values. *Supports:* - **DataType:** Discrete - **Field Type:** Date - **Fixed Value:** #YYYY-MM-DD, e.g. #2021-04-05 |

## JSON Sample

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

## Usage Notes

See also [DAYSAFTERMIN(A)](/v1/docs/engineeringdatefunction2-8)

## Example

| Example | Details |
| --- | --- |
| **Description** | Calculate age of a transaction in days |
| **Input** | - Table: = [transactions] - Function: = DateTransform - **DateTimeFunction: = DAYSBEFOREMAX(A)** - A:= [transactions].[last_response] - Name: = DaysBeforeMax |
| **Sample** | ![](https://cdn.document360.io/73b6469b-c1e4-47e9-aa65-986c8ebd17ca/Images/Documentation/DAYSBEFOREMAX_Example.PNG) |