Oracle SQL to Sort Version Numbers

In Oracle, just using the ORDER BY does not sort version numbers. My Version_Number field is declared as a VARCHAR and I cannot change it. For Example: The following versions :

1.20  
1.9   
1.18  
1.13  
1.5   
1.11  
2.0  
1.8   
1.3   
1.2   
1.1   
1.0   
1.10  

should be sorted as

2.0   
1.20  
1.18  
1.13 
1.11 
1.10  
1.9   
1.8   
1.5  
1.3   
1.2   
1.1 
1.0   

I have researched several posts but none of them seem to really serve my purpose or the answers were intended for SQL Server, etc and not Oracle. I came across this particular sql which seemed to look like it worked.

select version_number from mytable 
order by lpad(version_number, 4) desc;

which sorted the versions in this fashion:

1.20    
1.18   
1.13   
1.11   
1.10   
2.0    
1.9    
1.8   
1.5     
1.3    
1.2    
1.1    
1.0    

I believe this sql statement works for SQL Server :

select version_number from mytable 
order by cast ('/' + replace(version_number , '.', '/') + '/' as hierarchyid) desc;

However, this does not work with Oracle. Is there an alternative to hierarchyid in Oracle?


Is there anyone who can come up with a SQL to sort these versions accurately?

I have already seen the posts mentioned below (links attached). So kindly do not tell me that this post is a duplicate.
SQL sort by version "number", a string of varying length
How Can I Sort A 'Version Number' Column Generically Using a SQL Server Query
Version number sorting in Sql Server
mysql sorting of version numbers
and many more.

This is one way to do it. First order by the number before . and then by the numbers after .

select version_number 
from mytable 
order by substr(version_number, 1, instr(version_number,'.')-1) desc
        ,length(substr(version_number, instr(version_number,'.')+1)) desc
        ,substr(version_number, instr(version_number,'.')+1) desc