Can I use Cursor with stored procedure in MySQL? And can I receive the output values from it?
Yes;
CREATE PROCEDURE curdemo()
BEGIN
DECLARE done INT DEFAULT 0;
DECLARE a CHAR(16);
DECLARE b,c INT;
DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1;
DECLARE cur2 CURSOR FOR SELECT i FROM test.t2;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
OPEN cur1;
OPEN cur2;
REPEAT
FETCH cur1 INTO a, b;
FETCH cur2 INTO c;
IF NOT done THEN
IF b < c THEN
INSERT INTO test.t3 VALUES (a,b);
ELSE
INSERT INTO test.t3 VALUES (a,c);
END IF;
END IF;
UNTIL done END REPEAT;
CLOSE cur1;
CLOSE cur2;
END
Example taken from the manual.
Related
This is my current trigger:
DELIMITER $$
CREATE DEFINER=`root`#`127.0.0.1` TRIGGER `unique_visit_new_campaign` AFTER INSERT ON `unique_visit` FOR EACH ROW
BEGIN
DECLARE done INT DEFAULT FALSE;
DECLARE pixel_id int;
DECLARE campaign_id varchar(45);
DECLARE cur CURSOR FOR SELECT id FROM pixels;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur;
ins_loop: LOOP
FETCH cur INTO pixel_id;
IF done THEN
LEAVE ins_loop;
END IF;
INSERT IGNORE INTO pixels_campaign (campaign_id , pixel_id , date) VALUES (NEW.campaign_id ,pixel_id, current_timestamp);
END LOOP;
CLOSE cur;
END
I need it to NOT TRIGGER when new.campaign_id is empty or equals to the string {campaign_id}
I tried using MySQL IF but with no success.
Also, It kinda auto increment even when there is a campaign id already (when it ignores). any way I can stop that from happening?
Did you try this?
DELIMITER $$
CREATE DEFINER=`root`#`127.0.0.1` TRIGGER `unique_visit_new_campaign` AFTER INSERT ON `unique_visit` FOR EACH ROW
BEGIN
DECLARE done INT DEFAULT FALSE;
DECLARE pixel_id int;
DECLARE campaign_id varchar(45);
DECLARE cur CURSOR FOR SELECT id FROM pixels;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
IF new.campaign = '' or new.campaign = '{campaign_id}' or new.campaign is null THEN
OPEN cur;
ins_loop: LOOP
FETCH cur INTO pixel_id;
IF done THEN
LEAVE ins_loop;
END IF;
INSERT IGNORE INTO pixels_campaign (campaign_id , pixel_id , date) VALUES (NEW.campaign_id ,pixel_id, current_timestamp);
END LOOP;
CLOSE cur;
END IF
END
This is what i tried. I couldnt get my values inserted into table. can anyone help me out ..
DELIMITER $$
USE `SampleDB`$$
DROP PROCEDURE IF EXISTS `Sample`$$
CREATE PROCEDURE `SampleDB`.`Sample`()
BEGIN
#declare variable
DECLARE tenantName VARCHAR(255);
DECLARE tenantAddress VARCHAR(255);
DECLARE done INT DEFAULT FALSE;
DECLARE cur1 CURSOR FOR SELECT tenant_name,tenant_address FROM tenant;
#open cursor
OPEN cur1;
#starts the loop
the_loop: LOOP
#get the values of each column into our variables
FETCH cur1 INTO tenantName,tenantAddress;
IF done THEN
LEAVE the_loop;
END IF;
#Insert it
INSERT INTO tenant(tenant_name,tenant_address)
VALUES (tenantName,tenantAddress);
END LOOP the_loop;
CLOSE cur1;
END$$
DELIMITER ;
Indeed lack 13.6.7.2. DECLARE ... HANDLER Syntax:
...
DECLARE cur1 CURSOR FOR SELECT tenant_name, tenant_address FROM tenant;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done := TRUE;
#open cursor
...
But do you really need a cursor? With a statement like this, you can avoid the cursor:
INSERT INTO `tenant` (`tenant_name`, `tenant_address`)
SELECT `tenant_name`, `tenant_address` FROM `tenant`;
How to use for loop in MySQL data set ?
FOR x IN (SELECT column FROM table_name WHERE column_2 = input_val)
LOOP
sum_total := sum_total + x.column ;
END LOOP;
This is an example how I used to loop data set in oracle.
How can this be achieved in MySql ?
How about not looping at all. It's SQL after all.
SELECT SUM(`column`) total
FROM table_name
WHERE column_2 = <input_val>
Otherwise use CURSOR
Now, equivalent loop using CURSOR will look like
DELIMITER $$
CREATE PROCEDURE sp_loop(IN input_val INT)
BEGIN
DECLARE done INT DEFAULT FALSE;
DECLARE sum_current, sum_total INT DEFAULT 0;
DECLARE cur1 CURSOR FOR SELECT column1 FROM table_name WHERE column2 = input_val;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur1;
read_loop: LOOP
FETCH cur1 INTO sum_current;
IF done THEN
LEAVE read_loop;
END IF;
SET sum_total = sum_total + sum_current;
END LOOP;
CLOSE cur1;
SELECT sum_total;
END$$
DELIMITER ;
Here is SQLFiddle
DROP PROCEDURE IF EXISTS `foo`.`usp_cursor_example`;
DELIMITER $$
CREATE DEFINER=`root`#`localhost` PROCEDURE `foo`.`usp_cursor_example`(
IN name_in VARCHAR(255)
)
READS SQL DATA
BEGIN
DECLARE name_val VARCHAR(255);
DECLARE status_update_val VARCHAR(255);
-- Declare variables used just for cursor and loop control
DECLARE no_more_rows BOOLEAN;
DECLARE loop_cntr INT DEFAULT 0;
DECLARE num_rows INT DEFAULT 0;
-- Declare the cursor
DECLARE friends_cur CURSOR FOR
SELECT
name
, status_update
FROM foo.friend_status
WHERE name = name_in;
-- Declare 'handlers' for exceptions
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET no_more_rows = TRUE;
OPEN friends_cur;
select FOUND_ROWS() into num_rows;
the_loop: LOOP
FETCH friends_cur
INTO name_val
, status_update_val;
IF no_more_rows THEN
CLOSE friends_cur;
LEAVE the_loop;
END IF;
select name_val, status_update_val;
-- count the number of times looped
SET loop_cntr = loop_cntr + 1;
END LOOP the_loop;
-- 'print' the output so we can see they are the same
select num_rows, loop_cntr;
END
DELIMITER ;
What is the right method to reuse a cursor inside a mysql stored procedure?
We're doing it like below, and It just does not look correct. Does anyone know whats the right method to do this?
DELIMITER $$
USE `test`$$
DROP PROCEDURE IF EXISTS `fred`$$
CREATE DEFINER=`root`#`windows7.home` PROCEDURE `fred`()
BEGIN
DECLARE X INT;
DECLARE done INT DEFAULT FALSE;
DECLARE myType INT;
DECLARE cur1 CURSOR FOR SELECT val FROM checkval;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
SET X = 10;
WHILE X >= 2 DO
##############
OPEN cur1;
FETCH cur1 INTO myType;
read_loop: LOOP
IF done THEN
LEAVE read_loop;
END IF;
INSERT INTO myType VALUES (myType);
FETCH cur1 INTO myType;
END LOOP read_loop;
CLOSE cur1;
SET X = X-1;
SET done=FALSE;
##################
END WHILE;
END$$
DELIMITER ;
Heres the question that started it:
While loop in stored procedure loops only twice instead of 8 times
DELIMITER $$
CREATE PROCEDURE curdemo()
BEGIN
DECLARE done INT DEFAULT FALSE;
DECLARE b, c INT;
DECLARE cur1 CURSOR FOR SELECT empid FROM test.mytable;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur1;
read_loop: LOOP
FETCH cur1 INTO b;
IF done THEN
LEAVE read_loop;
END IF;
INSERT INTO test.test_log VALUES (b,'test');
CLOSE cur1;
END $$
When compiling this code I an getting 1064 error can some one pls help me to find the error
I think this will help u. Put END LOOP; before CLOSE cur1;