Advanced SQL: Employee Hires and Attrition

I have an employee roster, that I needed to compare month-over-month of who’s new (hires) and who left (attrition or turnover).

Original Solution

My original process was to run a SQL script, that created the dataset and placed it into a separate database table. This would be done manually each month once a new end-of-month roster became available.

Don’t worry coworkers; as with all examples, exact table names/fields are changed 😃

Proposed Solution

I ran into the problem where the original dataset kept changing, so I needed to constantly re-create the data. As you can see on lines 5 and 8 above, this would involve me updating the date and re-running the script for every month in my dataset.

I needed a solution where I could generate this data without the separate (extra) table:

New Hires:

Attrition / Turnover:

Final Solution

While the new/proposed solution works, I found other reasons to keep the old/original process. Specifically, I needed to massage the monthly data that required manual intervention.

At least now you, dear reader, have two solutions should you have this same need!