What is the opposite of GROUP_CONCAT in MySQL?

Issue

I seem to come against this problem a lot, where I have data that’s formatted like this:

+----+----------------------+
| id | colors               |
+----+----------------------+
| 1  | Red,Green,Blue       |
| 2  | Orangered,Periwinkle |
+----+----------------------+

but I want it formatted like this:

+----+------------+
| id | colors     |
+----+------------+
| 1  | Red        |
| 1  | Green      |
| 1  | Blue       |
| 2  | Orangered  |
| 2  | Periwinkle |
+----+------------+

Is there a good way to do this? What is this kind of operation even called?

Solution

I think it is what you need (stored procedure) : Mysql split column string into rows

DELIMITER $$

DROP PROCEDURE IF EXISTS explode_table $$
CREATE PROCEDURE explode_table(bound VARCHAR(255))

BEGIN

DECLARE id INT DEFAULT 0;
DECLARE value TEXT;
DECLARE occurance INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DECLARE splitted_value INT;
DECLARE done INT DEFAULT 0;
DECLARE cur1 CURSOR FOR SELECT table1.id, table1.value
                                     FROM table1
                                     WHERE table1.value != '';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

DROP TEMPORARY TABLE IF EXISTS table2;
CREATE TEMPORARY TABLE table2(
`id` INT NOT NULL,
`value` VARCHAR(255) NOT NULL
) ENGINE=Memory;

OPEN cur1;
  read_loop: LOOP
    FETCH cur1 INTO id, value;
    IF done THEN
      LEAVE read_loop;
    END IF;

    SET occurance = (SELECT LENGTH(value)
                             - LENGTH(REPLACE(value, bound, ''))
                             +1);
    SET i=1;
    WHILE i <= occurance DO
      SET splitted_value =
      (SELECT REPLACE(SUBSTRING(SUBSTRING_INDEX(value, bound, i),
      LENGTH(SUBSTRING_INDEX(value, bound, i - 1)) + 1), ',', ''));

      INSERT INTO table2 VALUES (id, splitted_value);
      SET i = i + 1;

    END WHILE;
  END LOOP;

  SELECT * FROM table2;
 CLOSE cur1;
 END; $$

Answered By – kmas

This Answer collected from stackoverflow, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0

Leave a Reply

(*) Required, Your email will not be published