MySQL中，如何根据日期选择数据？

Question

I need to get record based on date but I got stuck.我需要根据日期获取记录，但我被卡住了。

rate  applicable_date

12        01/01/2001
13.5      01/05/2005
17.9      07/11/2017

I need to get applicable rate based on applicable date.我需要根据适用日期获得适用费率。 I used below SQL:我使用了以下 SQL：

Select rate from ratetable where applicable_date <=$date;

For $date = '12/02/2017' ;对于$date = '12/02/2017' ;

It returns me 12它返回给我12

but for date 17/11/2017 it returns me all rates but I need only 17.9 latest one.但是对于 2017 年 17 月 11 日的日期，它会返回所有费率，但我只需要 17.9 最新的费率。

Answer 1

尝试执行以下查询

select rate from ratetable where applicable_date = $date

Answer 2

select rate 
from ratetable 
where applicable_date <=$date
order by desc
limit 1;

now it will return only 17.9现在它只会返回 17.9