MySQL splits fields through delimiters, that is, converting one row to multiple rows

1. The original data of the table is as follows:

SELECT id,warehouse_ids FROM `test` ORDER BY warehouse_ids DESC LIMIT 1

2. Split queries based on commas

Notice

1. The delimiter needs to be replaced with the corresponding character. Here I am comma (,)

2. The user table of JOIN is a table in my database. Its main purpose is to use its auto-increment id. The auto-increment id must start from 1 continuously (1, 2, 3....)

3. Generally, the mysql.help_topic table is used instead of user. Since there is no permission for this table, user is used instead.

SELECT
	t.id AS 'id',
	substring_index( substring_index( t.warehouse_ids, ',', h.id  ), ',',- 1 ) AS 'warehouse_id' 
FROM
	(SELECT id,warehouse_ids FROM `test` ORDER BY warehouse_ids DESC LIMIT 1) t
	JOIN user AS h ON h.id-1 < ( char_length( t.warehouse_ids ) - char_length( REPLACE ( t.warehouse_ids, ',', '' ) ) + 1 )

Referenced the following sql

SELECT
    t.id AS 'id',
    t.NAME AS '姓名',
    substring_index( substring_index( t.courses, '、', h.help_topic_id + 1 ), '、',- 1 ) AS '课程'
FROM t_student t JOIN mysql.help_topic AS h ON h.help_topic_id < ( char_length( t.courses ) - char_length( REPLACE ( t.courses, '、', '' ) ) + 1 )
;

3. Reference documents

MySQL splits fields through delimiters, that is, converting one row to multiple rows in SQL writing

mysql splits the string into multiple lines (separated by commas, etc.)