SELECT
    visit_date AS date,
    CONCAT(ROUND(100 * order_cnt / visit_cnt, 1), '%') AS cr
FROM(
SELECT
    DATE(leave_time) AS visit_date,
    COUNT(DISTINCT user_id) AS visit_cnt
FROM visit_tb vt
GROUP BY visit_date
) AS tb1
JOIN(
    SELECT
        DATE(order_time) AS order_date,
        COUNT(DISTINCT user_id) AS order_cnt
    FROM order_tb
    GROUP BY order_date
) AS tb2
ON tb1.visit_date = tb2.order_date
ORDER BY date ASC