在 MySQL 中创建计划事件

Question

I have a table names offer inside a MySQL database named fouras :

mysql> desc offer;
+------------------------+---------------+------+-----+---------+----------------+
| Field                  | Type          | Null | Key | Default | Extra          |
+------------------------+---------------+------+-----+---------+----------------+
| id                     | bigint(20)    | NO   | PRI | NULL    | auto_increment |
| description            | varchar(5000) | NO   |     | NULL    |                |
| end_date               | date          | NO   |     | NULL    |                |
| is_accepted            | bit(1)        | NO   |     | NULL    |                |
| is_active              | bit(1)        | NO   |     | NULL    |                |
| is_draft               | bit(1)        | NO   |     | NULL    |                |
| is_processed           | bit(1)        | NO   |     | NULL    |                |
| is_removed             | bit(1)        | NO   |     | NULL    |                |
| max_reservation_number | int(11)       | NO   |     | NULL    |                |
| promotion_first_param  | varchar(255)  | YES  |     | NULL    |                |
| promotion_product      | varchar(255)  | YES  |     | NULL    |                |
| promotion_second_param | varchar(255)  | YES  |     | NULL    |                |
| promotion_type         | varchar(255)  | NO   |     | NULL    |                |
| publish_date           | date          | YES  |     | NULL    |                |
| remove_time_stamp      | bigint(20)    | YES  |     | NULL    |                |
| start_date             | date          | NO   |     | NULL    |                |
| title                  | varchar(255)  | NO   |     | NULL    |                |
| views_number           | int(11)       | YES  |     | NULL    |                |
| local_business         | bigint(20)    | YES  | MUL | NULL    |                |
+------------------------+---------------+------+-----+---------+----------------+
19 rows in set (0.00 sec)

Now, i want to periodically check if an offer has expired (end_date > today), for that i'm trying to use a MySQL scheduled event :

CREATE EVENT IF NOT EXISTS check_expired_offers
    ON SCHEDULE EVERY 10 MINUTE
    DO
        BEGIN
            DECLARE id INT;
            DECLARE end_date DATE;
            DECLARE offer_cursor CURSOR FOR SELECT id, end_date FROM fouras.offer;

            OPEN offer_sursor;
            offer_loop: LOOP
                FETCH offer_cursor into id, end_date;
                IF end_date < NOW() THEN 
                    UPDATE fouras.offer set is_active = false;  
                END IF;

            END LOOP
END;

But MySQL throws an error when i try to add this event:

Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 5    0,127 sec

Answer 1

错误与分隔符有关，本教程对我帮助很大

Answer 2

==========================

Found delimiter issue.

==========================

Here's the modified event :

DELIMITER $$
CREATE EVENT IF NOT EXISTS check_expired_offers
    ON SCHEDULE EVERY 10 MINUTE
    DO
        BEGIN
            DECLARE finished INTEGER DEFAULT 0;
            DECLARE id INT;
            DECLARE end_date DATE;
            DECLARE offer_cursor CURSOR FOR SELECT id, end_date FROM fouras.offer;
                        DECLARE CONTINUE HANDLER FOR NOT FOUND SET finished = 1;

            OPEN offer_cursor;
            offer_loop: 
                        LOOP
                FETCH offer_cursor into id, end_date;
                IF finished = 1 THEN 
                                    LEAVE offer_loop;
                                END IF;
                                IF end_date < NOW() THEN 
                    UPDATE fouras.offer set is_active = false;  
                END IF;

            END LOOP ;
END $$
DELIMITER ;

Learn delimiters in MySQL

---

Note: I've also used a variable there named finished .

Where finished is a variable to indicate that the cursor has reached the end of the result set. Notice that the handler declaration must appear after variable and cursor declaration inside the stored programs.

---

The following diagram illustrates how MySQL cursor works.