Compare two columns in Excel

 If you have two large lists that you need to compare (to identify what items are missing in one of the lists), this can be done in excel.

Add the first list (the bigger of the two) in column A and the other list in column B.

For column C, add this formula in cell C2 and drag it all the way down to the bottom column C:

=IF(COUNTIF($B:$B; A2)=0; "Item in column A is missing in column B"; "Item exists in both lists")

What it does is for each cell in column A, it will run through all the items in column B and look for a match and note if it finds one, see screenshot below.

An example xlsx file is available on GitHub (choose download raw file).

Create architecture diagrams with Mermaid and ChatGPT

 Mermaid is a practical tool that can create all sorts of diagrams as code. And if you combine it with an LLM, you can create it with a prompt.

To view the results, go to https://mermaid.live and add the code in the box on the left.

As an example, I had ChatGPT create a hybrid cloud architecture diagram with an on-prem location connected to Azure via an ExpressRoute. For encryption, VPN runs inside the ER circuit. The Azure setup is hub-spoke meaning the central networking components are in the hub and are connected to multiple spoke VNets. Traffic flows through an Azure Firewall.

I have put the code in a markdown file on Github (click Raw to view code).

Result looks like below:

If saving the mermaid code in a markdown file (.md) it will render the diagram directly in Github as long as it is wrapped with ```mermaid at the beginning and ``` at the end.

And if you copy raw code to mermaid.live, only use the text inside the wrapper.

Here's what it looks like at mermaid.live:

You can also preview the diagram in Visual Studio Code if you install the Markdown Preview Mermaid Support extension (and save file as .md). To view diagram, just right-click the .md file and choose "Open preview". It looks like this:

The native Mermaid file format extension is .mmd and there are extensions for VS Code for that as well.