Find the Latest Date in a Series

Finding the Latest Date in Knack: A Simple Guide

Hello, I’m Dave Parrish from Knack Builders, and today I want to share a quick and practical tip on using Knack to find the latest date in a series of dates. This solution has been incredibly useful for me, and with some help from Knack support, I’ve streamlined the process. Let’s dive in!

Understanding the Context

Imagine we’re managing invoices with multiple line items, each associated with different service dates. For our invoicing needs, especially when submitting to government organizations, we need to determine the most recent date among these line items. Specifically, we need this date to be one day later for the request date. Let’s see how we can achieve this efficiently.

Setting Up the Data

In our Knack app, we have invoices akin to those in QuickBooks, and each invoice can have numerous service line items, each with its own date. The goal is to extract the latest date from these line items, so we can generate a request date automatically.

The Calculation Process

Here’s where the magic happens! Knack offers various functions, but finding the latest date isn’t straightforward since its built-in functions primarily deal with numerical data. So, I devised a workaround using date conversion.

Converting Dates to Numbers

First, we need to convert our date into a numerical format. This is where Unix time comes into play. Unix time counts the number of days since January 1, 1970. By converting our dates to numbers, we can easily manipulate them mathematically.

For example, a date like September 13, 2019, converts to a number that represents how many days it has been since that Unix epoch date.

Using the Max Function

Once we have our dates converted into numbers, we can then apply the max function to find the largest value among them. This tells us which date is the latest.

Final Steps: Back to Date

After identifying the maximum value, we convert that number back into a date format. Finally, we add one day to it for our request date. For instance, if the latest line item date is June 13, our request date will be June 14.

Automation in Action

With this setup, our app automatically calculates the request date, eliminating the need for manual entry. Here’s how it looks: for an invoice where the latest service date is June 13, the request date appears as June 14, all thanks to our calculations!

Conclusion

To sum it up: convert dates to numbers using Unix time, apply the max function to find the latest date, and then convert it back to a date, adding an extra day as required. This method is not only efficient but also ensures accuracy in our invoicing process.

Thank you for joining me today! I hope this quick tip helps streamline your own workflows in Knack. If you have any questions or need further assistance, feel free to reach out. Happy building!

You can check out my Knack database services here:  https://www.knackbuilders.com/knack-database-consulting

Interested? Book an intro call: https://calendly.com/daveparrish/callwithdave