按包含字母和数字的属性排序

Question

我们需要订购一份房间号列表。您可以认为单位是按数字排序的，前面可能有字母作为前缀，例如 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, A1, A2, A3, A4 、A5、A6、A7、A8、A9、A10、B1、B2、B3 等

阅读完MySQL“排序依据”-正确排序字母数字后，这是我尝试过的：

create table units (id integer, unit_number varchar(100));
    insert into units (id, unit_number) values (1, 'A1');
    insert into units (id, unit_number) values (2, 'A2');
    insert into units (id, unit_number) values (3, 'A3');
    insert into units (id, unit_number) values (4, 'A4');
    insert into units (id, unit_number) values (5, 'A5');
    insert into units (id, unit_number) values (6, 'A6');
    insert into units (id, unit_number) values (7, 'A7');
    insert into units (id, unit_number) values (8, 'A8');
    insert into units (id, unit_number) values (9, 'A9');
    insert into units (id, unit_number) values (10, 'A10');
    insert into units (id, unit_number) values (11, 'B1');
    insert into units (id, unit_number) values (12, 'B2');
    insert into units (id, unit_number) values (13, 'B3');
    insert into units (id, unit_number) values (14, 'B4');
    insert into units (id, unit_number) values (15, 'B5');
    insert into units (id, unit_number) values (16, 'B6');
    insert into units (id, unit_number) values (17, 'B7');
    insert into units (id, unit_number) values (18, 'B8');
    insert into units (id, unit_number) values (19, 'B9');
    insert into units (id, unit_number) values (20, 'B10');
    select * from units ORDER BY LENGTH(unit_number), unit_number;

当我得到结果时，我会得到这样的订单：

| id       | unit_number    |
| -------- | -------------- |
| 1        | A1             |
| 2        | A2             |
| 3        | A3             |
| 4        | A4             |
| 5        | A5             |
| 6        | A6             |
| 7        | A7             |
| 8        | A8             |
| 9        | A9             |
| 10       | B1             |
| 11       | B2             |
| 12       | B3             |
| 13       | B4             |
| 14       | B5             |
| 15       | B6             |
| 16       | B7             |
| 17       | B8             |
| 18       | B9             |
| 19       | A10            |
| 20       | B10            |

如何重写此查询，以便排序将 A10 放在 A9 之后？这更多是站在用户角度的期待。

Answer 1

您可以通过使用一些正则表达式来提取您需要的部分并对它们进行排序：

SELECT unit_number
FROM  units
ORDER BY
    SUBSTRING(unit_number FROM '^[A-Za-z]+'), -- This sorts the alphabetical part.
    CAST(SUBSTRING(unit_number FROM '[0-9]+$') AS INTEGER); -- This sorts the numerical part.

这也解决了更多字母字符的潜在问题，例如 AB123