Using SQL to determine cidr value of a subnet mask

Question

I\'d like to find a way to do a SQL query that will calculate the cidr (bit representation) of a subnet mask stored in the database. So for example, I\'ve got either 255.255.25

Answer 1

I think I have found the solution to my issue. Here is what I have done:

select CONCAT(INET_NTOA(ip_addr),'/',32-log2((4294967296-ip_mask))) net 
from subnets 
order by ip_addr

Basically I take my decmial mask and subtract it from the maximum decimal value. I then to a log2 on that value to get the logarithm value. Then simply subtract that from 32 (the maximum bit available).

Hope that helps others.

Thanks