A Simple Example of a MySQL Stored Procedure that uses a cursor
http://www.kbedell.com/2009/03/02/a-simple-example-of-a-mysql-stored-procedure-that-uses-a-cursor/
----
drop table if exists friend_status;
CREATE TABLE IF NOT EXISTS `friend_status` (
`id` INTEGER(10) unsigned NOT NULL auto_increment,
`name` VARCHAR(255) NOT NULL,
`status_update` VARCHAR(255) NOT NULL,
PRIMARY KEY (`id`)
);
insert into friend_status
(name, status_update)
values
('John', 'Woke up. Guiness for Brkfst.')
, ('Fred', 'is thinking about joining the circus')
, ('Erin', "Getting ready for a job interview")
, ('Amy', 'at work and dreaming of kittens')
, ('John', 'Watching Scooby Doo reruns. Guiness for Lunch.')
, ('Amy', 'dreaming of fuzzy slippers and wedding dresses')
, ('Julie', 'is hating working two jobs')
, ('John', 'Out of the shower finally. Guiness for Dinner.')
, ('Erin', "if I don't get this job, I'll be asking 'Paper or Plastic?'")
, ('Amy', 'dreaming of Meeting Mr. Right!')
, ('Erin', 'Nailed the job interview -- calling John to celebrate!')
, ('Amy', 'John called -- meeting him at the pub!')
, ('John', 'Heading out to meet friends for some Guiness!')
;
----
DROP PROCEDURE IF EXISTS `usp_cursor_example`;
DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `usp_cursor_example`(
IN name_in VARCHAR(255)
)
READS SQL DATA
BEGIN
/*
All 'DECLARE' statements must come first
*/
-- Declare '_val' variables to read in each record from the cursor
DECLARE name_val VARCHAR(255);
DECLARE status_update_val VARCHAR(255);
-- Declare variables used just for cursor and loop control
DECLARE no_more_rows BOOLEAN;
DECLARE loop_cntr INT DEFAULT 0;
DECLARE num_rows INT DEFAULT 0;
-- Declare the cursor
DECLARE friends_cur CURSOR FOR
SELECT name, status_update
FROM friend_status
WHERE name = name_in;
-- Declare 'handlers' for exceptions
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET no_more_rows = TRUE;
/*
Now the programming logic
*/
-- 'open' the cursor and capture the number of rows returned
-- (the 'select' gets invoked when the cursor is 'opened')
OPEN friends_cur;
select FOUND_ROWS() into num_rows;
the_loop: LOOP
FETCH friends_cur INTO name_val, status_update_val;
-- break out of the loop if
-- 1) there were no records, or
-- 2) we've processed them all
IF no_more_rows THEN
CLOSE friends_cur;
LEAVE the_loop;
END IF;
-- the equivalent of a 'print statement' in a stored procedure
-- it simply displays output for each loop
select name_val, status_update_val;
-- count the number of times looped
SET loop_cntr = loop_cntr + 1;
END LOOP the_loop;
-- 'print' the output so we can see they are the same
select num_rows, loop_cntr;
END
$$
DELIMITER ;