mysql循环数据

DELIMITER //

CREATE PROCEDURE process_data()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE id INT;
    DECLARE cur CURSOR FOR SELECT id FROM your_table;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO id;
        IF done THEN
            LEAVE read_loop;
        END IF;
        -- 处理每一行数据
        -- 例如：UPDATE your_table SET status = 'processed' WHERE id = id;
    END LOOP;

    CLOSE cur;
END //

DELIMITER ;

DELIMITER //

CREATE PROCEDURE process_data()
BEGIN
    DECLARE i INT DEFAULT 0;
    DECLARE total INT;

    SELECT COUNT(*) INTO total FROM your_table;

    WHILE i < total DO
        -- 处理每一行数据
        -- 例如：UPDATE your_table SET status = 'processed' WHERE id = i;
        SET i = i + 1;
    END WHILE;
END //

DELIMITER ;

SELECT t1.column1, t2.column2
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.id
WHERE t1.status = 'active';