优化Mysql UNION查询以加快加载速度

Question

我是一名初学者，我需要一些帮助来加速以下查询。在INDEXES中，我也是一名初学者，我不太明白如何添加和使用它们。 如果有人可以请帮助我加快这个查询，我会深表感谢。 目前查询花费~10s加载。

显示行0 - 0（1个总计，查询花费10.2243秒）

SELECT `location2` AS `location` , '2' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `country` = 'france' 
UNION SELECT `location3` AS `location` , '3' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location2` = 'france' 
UNION SELECT `location4` AS `location` , '4' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location3` = 'france' 
UNION SELECT `location5` AS `location` , '5' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location4` = 'france' 
UNION SELECT `location6` AS `location` , '6' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location5` = 'france' 

Answer 1

不要张开跨列的阵列。相反，请根据需要制作具有尽可能多行数的另一个表。

通过该更改，您可以避开UNION，我们可以讨论如何优化需要的JOIN。