MySQL Cookbook

Sorting Dotted-Quad IP Values in Numeric Order

Problem

You want to sort strings that represent IP numbers in numeric order.

Solution

Break apart the strings and sort the pieces numerically. Or just use INET_ATON( ).

Discussion

If a table contains IP numbers represented as strings in dotted-quad notation (for example, 111.122.133.144), they’ll sort lexically rather than numerically. To produce a numeric ordering instead, you can sort them as four-part values with each part sorted numerically. To accomplish this, use a technique similar to that for sorting hostnames, but with the following differences:

• Dotted quads always have four segments, so there’s no need to prepend dots to the value before extracting substrings.

• Dotted quads sort left to right, so the order in which substrings are used in the ORDER BY clause is opposite to that used for hostname sorting.

• The segments of dotted-quad values are numbers, so add zero to each substring to tell MySQL to using a numeric sort rather than a lexical one.

Suppose you have a hostip table with a string-valued ip column containing IP numbers:

mysql> SELECT ip FROM hostip ORDER BY ip;
+-----------------+
| ip              |
+-----------------+
| 127.0.0.1       |
| 192.168.0.10    |
| 192.168.0.2     |
| 192.168.1.10    |
| 192.168.1.2     |
| 21.0.0.1        |
| 255.255.255.255 |
+-----------------+

The preceding query produces output sorted in lexical order. To sort the ip values numerically, you can extract each segment and add zero to convert it to a number using an ORDER BY clause ...