MySQL 8.0

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CREATE TABLE tbl (
  id int(11) NOT NULL AUTO_INCREMENT,
  `timestamp` datetime DEFAULT NULL,
  direction varchar(10) DEFAULT NULL,
    PRIMARY KEY (`id`)
);
CREATE TABLE service (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, txt TEXT);
CREATE TRIGGER tr
AFTER INSERT
ON tbl
FOR EACH ROW
BEGIN
IF EXISTS ( SELECT 1
            FROM tbl t1, tbl t2
            WHERE t1.`timestamp` BETWEEN CURRENT_TIMESTAMP - INTERVAL 2 MINUTE
                                     AND CURRENT_TIMESTAMP + INTERVAL 2 MINUTE
              AND t2.`timestamp` BETWEEN CURRENT_TIMESTAMP - INTERVAL 7 MINUTE
                                     AND CURRENT_TIMESTAMP - INTERVAL 3 MINUTE
              AND t1.direction != t2.direction ) THEN
    IF 'SELL' = ( SELECT direction
                  FROM tbl
                  ORDER BY `timestamp` DESC LIMIT 1 ) THEN
        /* SELECT 1 INTO OUTFILE 'SELL.txt'; */
        INSERT INTO service (txt) VALUES (CONCAT(CURRENT_TIMESTAMP, ' SELL'));
    ELSE
        /* SELECT 1 INTO OUTFILE 'BUY.txt'; */ 
        INSERT INTO service (txt) VALUES (CONCAT(CURRENT_TIMESTAMP, ' BUY'));
    END IF;
END IF;
END
INSERT INTO tbl (`timestamp`, direction)
WITH RECURSIVE 
cte AS 
( 
SELECT CURRENT_TIMESTAMP ts
UNION ALL
SELECT ts - INTERVAL 5 MINUTE
FROM cte 
WHERE ts > CURRENT_TIMESTAMP - INTERVAL 30 MINUTE
)
SELECT ts, CASE WHEN RAND() > 0.5 THEN 'SELL' ELSE 'BUY' END
FROM cte;
SELECT * FROM tbl;
SELECT * FROM service;


id
timestamp
direction


1
2021-10-01 12:20:42
SELL

2
2021-10-01 12:15:42
SELL

3
2021-10-01 12:10:42
BUY

4
2021-10-01 12:05:42
BUY

5
2021-10-01 12:00:42
SELL

6
2021-10-01 11:55:42
BUY

7
2021-10-01 11:50:42
BUY

id	timestamp	direction
1	2021-10-01 12:20:42	SELL
2	2021-10-01 12:15:42	SELL
3	2021-10-01 12:10:42	BUY
4	2021-10-01 12:05:42	BUY
5	2021-10-01 12:00:42	SELL
6	2021-10-01 11:55:42	BUY
7	2021-10-01 11:50:42	BUY