Operation with values in query inside stored procedure (mysql) - mysql

Question

i have a stored procedure in mysql with a couple of queries and i need to perform some operations with that query.
This is some the code from the stored procedure:
BEGIN
SET ##session.collation_connection = ##global.collation_connection;
DROP TEMPORARY TABLE IF EXISTS innerContainers;
CREATE TEMPORARY TABLE `innerContainers` (
`id_container` INT(10) NOT NULL,
`display_name` VARCHAR(100) NOT NULL,
PRIMARY KEY (`id_container`)
)
ENGINE = memory;
INSERT INTO innerContainers(id_container, display_name)
(SELECT c1.id_container, c1.display_name
FROM container_presentation cp
LEFT JOIN presentation p USING(id_presentation)
LEFT JOIN container c1 ON p.id_container = c1.id_container
WHERE c1.isDeleted = 0 AND c1.isActive = 1 AND
cp.id_container = in_id_container)
UNION
(SELECT c1.id_container, c1.display_name
FROM container_assembly_item cp
LEFT JOIN presentation p USING(id_presentation)
LEFT JOIN container c1 ON p.id_container = c1.id_container
WHERE c1.isDeleted = 0 AND c1.isActive = 1 AND
cp.id_container = in_id_container);
SELECT mad.id_container,
mat.sign_stock,
ma.id_management_start_point,
ma.id_management_end_point,
mad.quantity
FROM management_activity ma
LEFT JOIN management_activity_type mat ON ma.id_management_activity_type = mat.id_management_activity_type
LEFT JOIN management_activity_detail mad ON ma.id_management_activity = mad.id_management_activity
LEFT JOIN management_stock_point msp ON ma.id_management_end_point = msp.id_management_stock_point
LEFT JOIN management_stock_point msp1 ON ma.id_management_start_point = msp1.id_management_stock_point
WHERE mad.id_container IN (SELECT id_container FROM innerContainers)
ORDER BY mad.id_container ASC;
END
Now, after the last query.. i need to do some operations and return a value for each id_container inside the temporary table depending on the values in the second query.
Something like this:
foreach id_container in the second query i have a resultValue and i need to:
if the sign_stock == 1 and some other conditions then resultValue -= quantity and if sign_stock == 2 and some other conditions then resultValue += quantity.
And the final resultValue after iterating over the id_container lines will be the one i want for that id_container in the temporary table.
I dont know how to do that operation.. can some one help me with that?

Answer 1

Don't create a temporary table unless you need the data after the procedure call. Either way, in order to iterate over the results of a SELECT query, use a CURSOR.
A simple example is provided in the linked manual page.