Natural Sorting SQL ORDER BY

Question

Can anyone lend me a hand as to what I should append to my ORDER BY statement to sort these values naturally:

1
10
2
22
20405-109
20405-101
20404-100
X
Z
D

Ideally I'd like something along the lines of:

1
2
10
22
20404-100
20405-101
20405-109
D
X
Z

I'm currently using:

ORDER BY t.property, l.unit_number

where the values are l.unit_number

I've tried doing l.unit_number * 1 and l.unit_number + 0 but they haven't worked.

Should I be doing sort of ORDER conditional, such as Case When IsNumeric(l.unit_number)?

Thank you.

Answer 1

This will do it:

SELECT value
FROM Table1
ORDER BY value REGEXP '^[A-Za-z]+$'
        ,CAST(value as SIGNED INTEGER)
        ,CAST(REPLACE(value,'-','')AS SIGNED INTEGER)
        ,value

The 4 levels of the ORDER BY:

1. REGEXP assigns any alpha line a 1 and non-alphas a 0
2. SIGNED INT Sorts all of the numbers by the portion preceding the dash.
3. SIGNED INT after removing the dash sorts any of the items with the same value before the dash by the portion after the dash. Potentially could replace number 2, but wouldn't want to treat 90-1 the same as 9-01 should the case arise.
4. Sorts the letters alphabetically.

Demo: SQL Fiddle