How to select values consisting of numerals only? I have a column like this:

WW0476091
YA0457514
547856232
856987452
254785W11


I want to get the values that contain numerals only (decimal digits from 0 to 9). For the example above, I want only these records to be printed:

547856232
856987452


How can I do that?
You can use a regular expression for that: 

select *
from the_table
where the_column ~ '^[0-9]+$';


Related question on Stackoverflow