如何用 SELECT 查询的结果覆盖整个表？（MySQL）

Question

通过以下查询，我创建一个表，该表是两个现有表左连接的结果：

CREATE TABLE meal_reservations
SELECT 
    meal.id, 
    meal.max_reservations, 
    SUM(IFNULL(reservation.number_of_guests, 0)) AS reservations
FROM meal
LEFT OUTER JOIN reservation 
ON meal.id = reservation.meal_id
GROUP BY meal.id;

我希望能够SELECT在需要时使用相同的查询更新其值。

我尝试过REPLACE INTO，但这只是将新结果附加到现有行上。

Answer 1

截断表然后用语句重新填充它怎么样insert ... select ...？这是我能想到的最简单的方法。否则，您将需要准确定义如何管理增量，这可能会很乏味。

-- empty the table
truncate table meal_reservations;

-- fill it again
insert into meal_reservations
SELECT 
    meal.id, 
    meal.max_reservations, 
    SUM(IFNULL(reservation.number_of_guests, 0)) AS reservations
FROM meal
LEFT OUTER JOIN reservation 
ON meal.id = reservation.meal_id
GROUP BY meal.id;