MySQL: prepared Statement in a stored Procedure - parameter error 1064 - mysql

Question

I'm creating a sql script for a migration functionality of ours. We want to migrate data from one magento-instance to another (using pure SQL because the import/export of magento is pretty limited).
One of the challenges ist that I want to dynamically alter the AUTO_INCREMENT value of a table so it doesn't need to be done manually in multiple steps. I want to set the AUTO_INCREMENT value to the current-maximum value of the corresponding column + 1.
I prepared the following stored procedure for this:
DELIMITER $$
CREATE PROCEDURE alter_auto_inc_customer()
BEGIN
SELECT #max := MAX(entity_id)+ 1 FROM customer_entity;
PREPARE stmt FROM 'ALTER TABLE customer_entity AUTO_INCREMENT = ?';
EXECUTE stmt USING #max;
END $$
This command runs smoothly. Afterwards the procedure should just be called by a simple statement:
CALL alter_auto_inc_customer();
When I execute the "call"-statement, I get a 1064 Syntax error. It's probably trivial but I can't figure it out for the life of me...
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?' at line 1
Does anyone have an idea what the issue is?
I need to get this into one or more stored procedures because I need to be able to run similar statements for multiple tables in the database.

Answer 1

Instead of altering the table structure you can use a trigger to get the max value + 1 before insert data:
DELIMITER $$
DROP TRIGGER IF EXISTS custom_autoincrement_bi$$
CREATE TRIGGER custom_autoincrement_bi BEFORE INSERT ON customer_entity
FOR each ROW
BEGIN
SET NEW.entity_id = select max(entity_id) + 1 from customer_entity;
END$$
DELIMITER ;
But if you want to alter the table from stored procedure
DELIMITER $$
CREATE PROCEDURE alter_auto_inc_customer()
BEGIN
SELECT MAX(entity_id) + 1 into #max FROM customer_entity;
set #sql = concat('ALTER TABLE customer_entity AUTO_INCREMENT = ', #max);
PREPARE stmt FROM #sql;
EXECUTE stmt ;
DEALLOCATE PREPARE stmt;
END $$