How to compare version string (“x.y.z”) in MySQL?

Question

I have firmware version strings into my table (like \"4.2.2\" or \"4.2.16\")

How can I compare, select or sort them ?

I cannot use standard strings compariso

Answer 1

Finally, I found another way to sort version strings.

I just justify the string before storing into de database in a way it is sortable. As I am using the python Django framework, I just have created a VersionField that 'encode' the version string while storing and 'decode' it while reading, so that it is totally transparent for the application :

Here my code :

The justify function :

def vjust(str,level=5,delim='.',bitsize=6,fillchar=' '):
    """
    1.12 becomes : 1.    12
    1.1  becomes : 1.     1
    """
    nb = str.count(delim)
    if nb < level:
        str += (level-nb) * delim
    return delim.join([ v.rjust(bitsize,fillchar) for v in str.split(delim)[:level+1] ])

The django VersionField :

class VersionField(models.CharField) :

    description = 'Field to store version strings ("a.b.c.d") in a way it is sortable'

    __metaclass__ = models.SubfieldBase

    def get_prep_value(self, value):
        return vjust(value,fillchar=' ')

    def to_python(self, value):
        return re.sub('\.+$','',value.replace(' ',''))