How to get the closest value that is less than a given one?

Question

PostgreSQL

There is a table with numbers. The table is sorted in ascending order of these numbers. How can I find a table row with a number closest to a given number (let's say 100) but less than it?

Answer 1

A separate row with the closest value to the specified one can be obtained like this

SELECT *
  FROM my_numbers
 WHERE my_num < 100
 ORDER BY my_num desc
 LIMIT 1