MYSQL cursor loop, runs one extra round, why?

Question

I'm looping through a cursor result set in a MYSQL stored procedure. I'm facing an issue which is that the loop always run thorough the last record twice. Here is my code,

BEGIN
DECLARE not_found_creadit INT DEFAULT 0;

DECLARE cur_credit CURSOR FOR 
SELECT customer_id, amount, status, user_type, employee, note FROM credit WHERE status = 'approved' AND customer_id = int_cust_id;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET not_found_creadit = 1;
OPEN cur_credit;
  SET not_found_creadit = 0;
  credit_loop : LOOP 
      IF not_found_creadit THEN
        CLOSE cur_credit;
        LEAVE credit_loop;
      END IF;
      FETCH cur_credit INTO vc_customer, dec_amount, vc_status, vc_user_type, vc_emp, vc_note;
      SELECT vc_customer, dec_amount, vc_status, vc_user_type, vc_emp, vc_note;
      ......
      ......
  END LOOP;
END;

Means if I have 3 records, loop runs 4 times, if it is 10 records loop runs 11 times, etc. Any idea whats happening here?

Answer 1

The handler, which sets not_found_creadit = 1, is fired when the FETCH returns no rows, but you are checking its value before executing FETCH, so the main body of your loop will execute one extra time when the FETCH fails, then the loop loop exits at the start of the next iteration.

Rearrange your code to check the value of your variable immediately after the FETCH:

credit_loop : LOOP 
    FETCH cur_credit INTO vc_customer, dec_amount, vc_status, vc_user_type, vc_emp, vc_note;
    IF not_found_creadit THEN
        CLOSE cur_credit;
        LEAVE credit_loop;
    END IF;
    SELECT vc_customer, dec_amount, vc_status, vc_user_type, vc_emp, vc_note;
    ......
    ......
END LOOP;

Also, consider correcting the spelling of your variable to not_found_credit