Mysql - How to use user defined variables on pointers - mysql

Question

I´m new to InnoDB and starting with transactions. I´ve been 24 hours trying to get this to work.
I´m creating an exchange site and really need a transaction to be made. First, make a Select and find some data, and then some updates and inserts according with the results given.
I won´t post the full query as it might be very complicated to read so I created a new query to point out whats bothering.
Table Log
CREATE TABLE `log` (
`num_rows` int(10) unsigned NOT NULL,
`new_value` int(10) unsigned NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Stored Procedure
DROP PROCEDURE IF EXISTS `test`//
CREATE PROCEDURE `test` (IN var1 BIGINT)
BEGIN
DECLARE done INT DEFAULT 0;
DECLARE result INT;
DECLARE num_rows INT;
DECLARE cur1 CURSOR FOR
SELECT #var1 := #var1 +1 AS result;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
START TRANSACTION;
OPEN cur1;
SELECT FOUND_ROWS() into num_rows;
INSERT INTO log (num_rows,new_value) VALUES (num_rows,var1);
read_loop:
LOOP
FETCH cur1 INTO result;
IF done = 1 THEN
LEAVE read_loop;
END IF;
END LOOP read_loop;
CLOSE cur1;
COMMIT;
END//
When I try
CALL test(1);
Im passing 1 as var1 parameter. So in cur1, the value should be increased. And later insert a new row to the log with the new value. It looks like := asignment isn´t working.
I actually changed
SELECT #var1 := #var1 +1 AS result;
for this
SELECT var1 := var1 +1 AS result;
And get an error on ":= var1 +1"

Answer 1

I understand that the code of the question is an abstraction of the actual code of the stored procedure, so do not quite understand what you need to do, however, a code like this can be helpful.
/* Procedure structure for procedure `test` */
/*!50003 DROP PROCEDURE IF EXISTS `test` */;
DELIMITER $$
CREATE PROCEDURE `test`(IN `var1` BIGINT)
BEGIN
DECLARE `done` TINYINT(1) DEFAULT 0;
DECLARE `result` BIGINT;
DECLARE `_num_rows` INT;
DECLARE `cur1` CURSOR FOR
SELECT SQL_CALC_FOUND_ROWS #`var1` := `var1` + 1;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET `done` := 1;
START TRANSACTION;
OPEN `cur1`;
SET `var1` := #`var1`;
SELECT FOUND_ROWS() INTO `_num_rows`;
INSERT INTO `log` (`num_rows`, `new_value`) VALUES (`_num_rows`, `var1`);
`read_loop`: LOOP
FETCH `cur1` INTO `result`;
IF (`done`) THEN
LEAVE `read_loop`;
END IF;
END LOOP `read_loop`;
CLOSE `cur1`;
COMMIT;
END$$
DELIMITER ;
It is important to indicate the difference between 9.4. User-Defined Variables and routine parameters 13.1.15. CREATE PROCEDURE and CREATE FUNCTION Syntax, are different variables.
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