Postgres query to check a string is a number

Question

Can anyone tell me the query to check whether a string is a number(double precision). It should return true if the string is number. else it should return false.

consider :

       s1 character varying;        s2 character varying;         s1 ='12.41212' => should return true        s2 = 'Service' => should return false 

Answer 1

I think the easiest way would be a regular expression match:

select '12.41212' ~ '^[0-9\.]+$' => true  select 'Service' ~ '^[0-9\.]+$' => false