MySQL custom split stored procedure

        MySQL does not provide the split function, but you can create a stored procedure yourself to convert a string with fixed delimiters into multiple rows. The reason why you cannot use custom functions to implement this function is because MySQL's custom functions can return scalar values ​​and cannot return multi-row result sets.

MySQL 8：

drop procedure if exists sp_split;
delimiter //
create procedure sp_split(p_str text, p_delimiter varchar(100))
begin
    select substring_index(substring_index(p_str, p_delimiter, lv), p_delimiter, - 1) a
      from (
	  with recursive tab1(lv) as (
           select 1 lv 
            union all
           select t1.lv + 1 from tab1 t1 
            where lv < (char_length(p_str) - char_length(replace(p_str, p_delimiter, ''))) / (char_length(p_delimiter)) + 1)
      select * from tab1
      ) t1;
end;
//
delimiter ;

MySQL 5：

drop procedure if exists sp_split;
delimiter //
create procedure sp_split(p_str text, p_delimiter varchar(100))
begin
    select substring_index(substring_index(p_str, p_delimiter, help_topic_id + 1), p_delimiter, - 1) a
      from mysql.help_topic  
     where help_topic_id < (char_length(p_str) - char_length(replace(p_str, p_delimiter, ''))) / (char_length(p_delimiter)) + 1;
end;
//
delimiter ;

test:

mysql> set @a:='123,456,789';
Query OK, 0 rows affected (0.00 sec)

mysql> call sp_split(@a,',');
+------+
| a    |
+------+
| 123  |
| 456  |
| 789  |
+------+
3 rows in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql> set @a:='中；；English；；混杂；；多字符分隔符';
Query OK, 0 rows affected (0.00 sec)

mysql> call sp_split(@a,'；；');
+--------------------+
| a                  |
+--------------------+
| 中                 |
| English            |
| 混杂               |
| 多字符分隔符        |
+--------------------+
4 rows in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)