Question

I've a table called idx with following data

id dex          
-- ------------ 
1  Major 12354  
2  CITY 541 DER 
3  9987741221   
4  7845741      
5  789456 2121

how to select rows with only digits and it should 10 digits only

expected output is

id dex         
-- ----------- 
3  9987741221  
5  789456 2121

Answer 1

You can use regex to match your criteria ^[0-9]{10,10}$, and I've used replace() function to remove empty space between characters(dex in id 5)

select * 
from idx 
where replace(dex,' ','')~'^[0-9]{10,10}$' -- or '^[0-9]{10,}$'

^[0-9]{10,10}$ :

[0-9] - To get digits

{10,10}$ - Maximum and minimum value in selected string in your case both are 10

OR

Using char_length()

select *
from idx 
where  dex~'^[0-9]' 
       and char_length(replace(dex,' ','')) = 10