mysql 日期相減，獲取天數

查詢系統當前時間，不帶時分秒，如：2018-11-02==>SELECT CURDATE();

日期相減函數，獲取天數：datediff(CURDATE(), '2018-01-01')

下面一個demo：

SELECT 
CASE 
WHEN datediff(CURDATE(), a.year_for_car) < 180 THEN '6個月以下'
WHEN 180<= datediff(CURDATE(), a.year_for_car) AND datediff(CURDATE(), a.year_for_car) <= 365 THEN '6~12個月'
WHEN 365<= datediff(CURDATE(), a.year_for_car) AND datediff(CURDATE(), a.year_for_car) <= 730 THEN '1~2年'
WHEN 730<= datediff(CURDATE(), a.year_for_car) AND datediff(CURDATE(), a.year_for_car) <= 1095 THEN '2~3年'
WHEN 1095<= datediff(CURDATE(), a.year_for_car) THEN '3年以上'
ELSE 0
END as abc
FROM table_a a;