Get only digits using regexp

https://stackoverflow.com/questions/16922248/get-only-digits-using-regexp/16922465

I have in table column pnum_s

I need get only that rows, which value in column pnum_s is exactly 10 symbol and all these symbols are only digits

what query must write for this?

I am trying

SELECT * FROM mytable WHERE pnum_s REGEXP '^\d+$'

The pattern you are looking for is either '^[0-9]{10}$' or '^[[:digit:]]{10}$'.

Everything is in the manual.