CODEWITHSUNDEEP
mysqlloopstriggers
Johan Hjalmarsson
Johan Hjalmarsson

Reputation: 3493

Loop through temporary table in trigger

I have this trigger that cointains a temporary table. Now I wish to loop through the temporary table and do something on each row. Is there some easy way of doing this? I have googled but everything seems overly complicated for such a simple task.

CREATE TRIGGER myTrigger AFTER UPDATE ON myTable
FOR EACH ROW
BEGIN
IF NEW.col <> OLD.col THEN
    DROP TEMPORARY TABLE IF EXISTS tmpTable;
    CREATE TEMPORARY TABLE IF NOT EXISTS tmpTable AS (my select statement);
    --For each row in tempTable--
        Do something
    --
    DROP TEMPORARY TABLE tmpTable;
END IF;
END

Upvotes: 1

Views: 5271

Answers (1)

jaczes
jaczes

Reputation: 1394

to have rownumber You can do:

DROP TEMPORARY TABLE IF EXISTS tmpTable;
CREATE TEMPORARY TABLE IF NOT EXISTS tmpTable AS (
SELECT  l.*,
    @curRow := @curRow + 1 AS row_no
FROM    XXX_TABLE l
JOIN    (SELECT @curRow := 0) r);

to use it You can use WHILE loop:

DECLARE n INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
SELECT COUNT(*) FROM tmpTable INTO n;
SET i=0;
WHILE i<n DO 
  SET i = i + 1;

  -- do sth WHERE row_no=i;

END WHILE;

Upvotes: 6

Related Questions