mysql如何遍历数据库

SELECT * FROM users;

DECLARE cur CURSOR FOR SELECT * FROM users;
DECLARE @id INT, @name VARCHAR(255);

OPEN cur;
FETCH NEXT FROM cur INTO @id, @name;

WHILE @@FETCH_STATUS = 0
BEGIN
    -- 处理每一行数据
    PRINT CONCAT('ID: ', @id, ', Name: ', @name);

    FETCH NEXT FROM cur INTO @id, @name;
END

CLOSE cur;
DEALLOCATE cur;

DELIMITER $$
CREATE PROCEDURE traverse_users()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE id INT;
    DECLARE name VARCHAR(255);
    DECLARE cur CURSOR FOR SELECT id, name FROM users;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO id, name;
        IF done THEN
            LEAVE read_loop;
        END IF;
        
        -- 处理每一行数据
        SELECT CONCAT('ID: ', id, ', Name: ', name);

    END LOOP;

    CLOSE cur;
END$$
DELIMITER ;

-- 调用存储过程
CALL traverse_users();