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POSELECT works on its own but returns 0 rows when assigned to a cursor
 

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  1. POSELECT works on its own but returns 0 rows when assigned to a cursor
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    <p>I have a SELECT statement which works on its own, and returns ~8000 rows. I am trying to add it to a stored procedure as a cursor but it's returning nothing.</p> <p>Can you spot anything I've missed?</p> <p><strong>Works</strong></p> <pre><code>SELECT a.customer, a.order_id FROM temp_orders a INNER JOIN ( SELECT customer, MAX(order_id) AS last_order FROM temp_orders WHERE pay_status = 3 OR pay_status = 4 GROUP BY customer ) AS b ON a.customer = b.customer AND a.order_id = b.last_order WHERE pay_status = 3 OR pay_status = 4 ORDER BY a.customer; </code></pre> <p><strong>No longer works</strong></p> <pre><code>DELIMITER // DROP PROCEDURE IF EXISTS get_last_orders // CREATE PROCEDURE get_last_orders() BEGIN DECLARE order_id VARCHAR(15); DECLARE customer_id INT; DECLARE done INT DEFAULT 0; DECLARE cur1 CURSOR FOR SELECT a.customer, a.order_id FROM temp_orders a INNER JOIN ( SELECT customer, MAX(order_id) AS last_order FROM temp_orders WHERE pay_status = 3 OR pay_status = 4 GROUP BY customer ) AS b ON a.customer = b.customer AND a.order_id = b.last_order WHERE pay_status = 3 OR pay_status = 4 ORDER BY a.customer; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; DROP TABLE IF EXISTS temp_last_orders; CREATE TABLE temp_last_orders ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, order_id VARCHAR(15) NOT NULL, customer_id INT NOT NULL ) ENGINE = MYISAM COMMENT = 'Last paid order from each customer'; OPEN cur1; read_loop: LOOP FETCH cur1 INTO order_id, customer_id; IF done THEN LEAVE read_loop; END IF; INSERT INTO temp_last_orders (order_id, customer_id) VALUES (order_id, customer_id); END LOOP; CLOSE cur1; END; // CALL get_last_orders(); </code></pre>
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    1. USBadHorsie
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    1. COMaybe there is a problem with variables and column names having the same name. Try renaming variables order_id and customer_id into, for example, v_order_id and v_customer_id and give it a try.
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      1. USMikhail
    2. CO@Mikhail Great, thanks! That was the problem. Post as an answer and I will accept.
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      1. USBadHorsie
    3. CO@BadHorsie Glad, that helped :) Added an answer.
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      1. POSELECT works on its own but returns 0 rows when assigned to a cursor
      1. USMikhail
 

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