How to split comma separated text in MySQL stored procedure

Question

How to split comma separated text (list of IDs) in MySQL stored procedure to use result in SQL \"IN\" statement.

SELECT * FROM table WHERE table.id IN (split         


        

Answer 1

You can do it two ways:

1. SQL Library
2. Natively with REGEXP

Answer 2

You could try this MySql example. Before you use it, put some type safety checks in there (i.e. check id is integer, or match against regular expression before insert).

 # BEGIN split statements ids
 DECLARE current_pos INT DEFAULT 1;
 DECLARE delim CHAR DEFAULT ',';
 DECLARE current CHAR DEFAULT '';
 DECLARE current_id VARCHAR(100) DEFAULT '';;
 CREATE TEMPORARY TABLE ids (`id` VARCHAR(100));
 split_ids: LOOP
  SET current = MID(statement_ids, current_pos, 1);
  IF (current_pos = LENGTH(statement_ids)) THEN
   IF current != delim THEN SET current_id = CONCAT(current_id,current); END IF;
   INSERT INTO ids(id) VALUES (current_id);
   LEAVE split_ids;
  END IF;
  IF current = delim THEN
   INSERT INTO ids(id) VALUES (current_id);
   SET current_id = '';
  ELSE
   SET current_id = CONCAT(current_id,current);
  END IF;
  SET current_pos = current_pos+1;
 END LOOP split_ids;
 # END split statement ids

 # to check ids are correct
 SELECT * FROM ids;

 # to use the ids:
 SELECT * FROM statements WHERE id IN (SELECT id FROM ids);

Answer 3

A bit strange but:

SET @i = 1;
set @str = 'a,b,c,d,e,f,g,h';

select temp.length into @length from 
(select
        ROUND(   
            (
                LENGTH(dt.data)
                - LENGTH( REPLACE (dt.data, ",", "") ) 
            ) / LENGTH(",")        
        )+1 AS length   
     from (select @str as data) dt
 ) temp;

SET @query = CONCAT('select substring_index(
    substring_index(@str, '','', seq), 
    '','', 
    -1
  ) as letter from seq_', @i, '_to_',@length);

PREPARE q FROM @query;
EXECUTE q;