Loop over table and call stored procedure - mysql

Question

Right now, i am trying to loop over a temporary table, that an import process created. I've tried using a cursor, but the tablename must be passed to the stored procedure.
CREATE PROCEDURE `do_update`(tablename VARCHAR(100))
BEGIN
DECLARE done BOOLEAN DEFAULT FALSE;
DECLARE c_ean VARCHAR(20);
DECLARE c_sku VARCHAR(20);
DECLARE c_mpn VARCHAR(20);
DECLARE c_manufacturerName VARCHAR(100);
DECLARE c_manufacturerUniqueId VARCHAR(100);
DECLARE c_images TEXT;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done := TRUE;
-- move declare cursor into sql to be executed
SET #sqlstatement = CONCAT('DECLARE import_cursor CURSOR FOR SELECT ean, sku, mpn, manufacturerName, manufacturerUniqueId, images FROM ', tablename);
PREPARE stmt FROM #sqlstatement;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
OPEN import_cursor;
importloop: LOOP
FETCH import_cursor INTO c_ean, c_sku, c_mpn, c_manufacturerName, c_manufacturerUniqueId, c_images;
IF done THEN
LEAVE importloop;
END IF;
CALL upsert_article(c_ean, c_sku, c_mpn, c_manufacturerName, c_manufacturerUniqueId, c_images);
END LOOP testloop;
CLOSE import_cursor;
END
Note: This import script will be called several times over the day and could be run concurrently. So a defined tablename is not an option.
What i have tried so far:
Creating a cursor with given tablename. --> Works, but the name must be dynamic.
Creating a cursor with dynamic sql. --> Failed
Skip using cursors and loop over table in a different way. --> No method found for using dynamic sql
So, is there a way to make this work with a cursor or a workaround?

Answer 1

Creating a temporary table and inserting the results of my dynamic query did the trick at the end.
With that i was able to use mysql cursor with the static named temporary table. And since it is an temporary table, multiple import-jobs won't interfere with each other, because they are hidden to other sessions.
In the end this is the code, that worked for me:
CREATE PROCEDURE `do_update`(IN
tablename VARCHAR(100))
BEGIN
DECLARE done INT;
DECLARE c_ean VARCHAR(20);
DECLARE c_sku VARCHAR(20);
DECLARE c_mpn VARCHAR(20);
DECLARE c_manufacturerName VARCHAR(100);
DECLARE c_manufacturerUniqueId VARCHAR(100);
DECLARE c_images NVARCHAR(3000);
DECLARE import_cursor CURSOR FOR SELECT ean, sku, mpn, manufacturerName, manufacturerUniqueId, images FROM importjob;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done := TRUE;
DROP TEMPORARY TABLE IF EXISTS importjob;
SET #sqlstatement = CONCAT('CREATE TEMPORARY TABLE importjob SELECT ean, sku, mpn, manufacturerName, manufacturerUniqueId, images FROM ', tablename);
PREPARE stmt FROM #sqlstatement;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET #DEBUG = true;
OPEN import_cursor;
importloop: LOOP
FETCH import_cursor INTO c_ean, c_sku, c_mpn, c_manufacturerName, c_manufacturerUniqueId, c_images;
IF done THEN
LEAVE importloop;
END IF;
CALL upsert_article(c_ean, c_sku, c_mpn, c_manufacturerName, c_manufacturerUniqueId, c_images);
END LOOP importloop;
CLOSE import_cursor;
DROP TEMPORARY TABLE IF EXISTS importjob;
END