排序 SQL 表

Question

i have SQL Table with following Infos :

    CREATE TABLE `cities` (
  `city_id` int(11) NOT NULL,
  `city` varchar(50) NOT NULL,
  `state_id` int(11) NOT NULL,
  `is_default` int(1) DEFAULT '1',
  `is_active` int(1) NOT NULL DEFAULT '1',
  `sort_order` int(11) NOT NULL DEFAULT '9999',
  `lang` varchar(10) NOT NULL DEFAULT 'en',
  `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `updated_at` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT;

The Problem is sort_order is empty ...

How can i sortorder the Table first to state_id -> then order the city to Alphabetic and fill the sort_order from 1 - *

Answer 1

You can use order by in an update :

set @rn := 0

update cities
    set sort_order = (@rn := @rn + 1)
    order by state_id, city;

Answer 2

Assuming MySQL 8.0, you can use row_number() .

I would not actually storing this derived information in the table itself; when data changes, you might need to renumber many rows.

Instead, you can compute this information on the fly when needed, or use a view:

select c.*, row_number() over(order by state_id, city) sort_order
from cities c

In earlier versions, you can achieve the same results with variables:

select c.*, (@rn := @rn + 1) sort_order
from cities c
cross join (select @rn := 1 rn) r