SQL: Select most recent date for each category

Question

I\'m pulling data from a database and one of the tables contain two columns that together identify a location and another column containing a date of each time it was servic

Answer 1

This is a simple "group by" using the fact the the "most recent" date is the "highest valued", or max(), date

select category_a, category_b, max(date)
from mytable
group by category_a, category_b
order by category_a, category_b -- The ORDER BY is optional, but the example data suggests it's needed