SQL query to find max primary key with custom format

Question

I have a data table which the primary key is formatted like M00001, M00002, M00003 ... so on. They are all string type. Is there any way to query the database to find the max primary key?

Answer 1

select max(id)
from t

If the RDBMS does not support max() then:

select id
from t
order by id desc
limit 1